diff --git a/lib/myprofilelib.php b/lib/myprofilelib.php
index 57a90741849..eb6baaa394e 100644
--- a/lib/myprofilelib.php
+++ b/lib/myprofilelib.php
@@ -299,7 +299,8 @@ function core_myprofile_navigation(core_user\output\myprofile\tree $tree, $user,
                 $groupstr = '';
                 foreach ($usergroups as $group) {
                     if ($course->groupmode == SEPARATEGROUPS and !$accessallgroups and $user->id != $USER->id) {
-                        if (!groups_is_member($group->id, $user->id)) {
+                        // In separate groups mode, I only have to see the groups shared between both users.
+                        if (!groups_is_member($group->id, $USER->id)) {
                             continue;
                         }
                     }
diff --git a/user/lib.php b/user/lib.php
index 020ccc11fa4..463228b277a 100644
--- a/user/lib.php
+++ b/user/lib.php
@@ -400,21 +400,21 @@ function user_get_user_details($user, $course = null, array $userfields = array(
     // Hidden user field.
     if ($canviewhiddenuserfields) {
         $hiddenfields = array();
-        // Address, phone1 and phone2 not appears in hidden fields list but require viewhiddenfields capability
-        // according to user/profile.php.
-        if (!empty($user->address) && in_array('address', $userfields)) {
-            $userdetails['address'] = $user->address;
-        }
     } else {
         $hiddenfields = array_flip(explode(',', $CFG->hiddenuserfields));
     }
 
-    if (!empty($user->phone1) && in_array('phone1', $userfields) &&
-            (in_array('phone1', $showuseridentityfields) or $canviewhiddenuserfields)) {
+
+    if (!empty($user->address) && (in_array('address', $userfields)
+            && in_array('address', $showuseridentityfields) || $isadmin)) {
+        $userdetails['address'] = $user->address;
+    }
+    if (!empty($user->phone1) && (in_array('phone1', $userfields)
+            && in_array('phone1', $showuseridentityfields) || $isadmin)) {
         $userdetails['phone1'] = $user->phone1;
     }
-    if (!empty($user->phone2) && in_array('phone2', $userfields) &&
-            (in_array('phone2', $showuseridentityfields) or $canviewhiddenuserfields)) {
+    if (!empty($user->phone2) && (in_array('phone2', $userfields)
+            && in_array('phone2', $showuseridentityfields) || $isadmin)) {
         $userdetails['phone2'] = $user->phone2;
     }
 
@@ -436,6 +436,10 @@ function user_get_user_details($user, $course = null, array $userfields = array(
         $userdetails['city'] = $user->city;
     }
 
+    if (in_array('timezone', $userfields) && (!isset($hiddenfields['timezone']) || $isadmin) && $user->timezone) {
+        $userdetails['timezone'] = $user->timezone;
+    }
+
     if (in_array('suspended', $userfields) && (!isset($hiddenfields['suspended']) or $isadmin)) {
         $userdetails['suspended'] = (bool)$user->suspended;
     }
@@ -518,17 +522,25 @@ function user_get_user_details($user, $course = null, array $userfields = array(
         }
     }
 
-    // If groups are in use and enforced throughout the course, then make sure we can meet in at least one course level group.
-    if (in_array('groups', $userfields) && !empty($course) && $canaccessallgroups) {
-        $usergroups = groups_get_all_groups($course->id, $user->id, $course->defaultgroupingid,
-                'g.id, g.name,g.description,g.descriptionformat');
-        $userdetails['groups'] = array();
-        foreach ($usergroups as $group) {
-            list($group->description, $group->descriptionformat) =
-                external_format_text($group->description, $group->descriptionformat,
-                        $context->id, 'group', 'description', $group->id);
-            $userdetails['groups'][] = array('id' => $group->id, 'name' => $group->name,
-                'description' => $group->description, 'descriptionformat' => $group->descriptionformat);
+    // Return user groups.
+    if (in_array('groups', $userfields) && !empty($course)) {
+        if ($usergroups = groups_get_all_groups($course->id, $user->id)) {
+            $userdetails['groups'] = [];
+            foreach ($usergroups as $group) {
+                if ($course->groupmode == SEPARATEGROUPS && !$canaccessallgroups && $user->id != $USER->id) {
+                    // In separate groups, I only have to see the groups shared between both users.
+                    if (!groups_is_member($group->id, $USER->id)) {
+                        continue;
+                    }
+                }
+
+                $userdetails['groups'][] = [
+                    'id' => $group->id,
+                    'name' => format_string($group->name),
+                    'description' => format_text($group->description, $group->descriptionformat, ['context' => $context]),
+                    'descriptionformat' => $group->descriptionformat
+                ];
+            }
         }
     }
     // List of courses where the user is enrolled.
@@ -560,7 +572,7 @@ function user_get_user_details($user, $course = null, array $userfields = array(
     }
 
     if ($currentuser or has_capability('moodle/user:viewalldetails', $context)) {
-        $extrafields = ['auth', 'confirmed', 'lang', 'theme', 'timezone', 'mailformat'];
+        $extrafields = ['auth', 'confirmed', 'lang', 'theme', 'mailformat'];
         foreach ($extrafields as $extrafield) {
             if (in_array($extrafield, $userfields) && isset($user->$extrafield)) {
                 $userdetails[$extrafield] = $user->$extrafield;
diff --git a/user/tests/behat/view_full_profile.feature b/user/tests/behat/view_full_profile.feature
index 5a0071f0922..75e6220d096 100644
--- a/user/tests/behat/view_full_profile.feature
+++ b/user/tests/behat/view_full_profile.feature
@@ -9,17 +9,19 @@ Feature: Access to full profiles of users
       | username | firstname | lastname | email |
       | student1 | Student | 1 | student1@example.com |
       | student2 | Student | 2 | student2@example.com |
-      | student3 | Student | 3 | student2@example.com |
+      | student3 | Student | 3 | student3@example.com |
       | teacher1 | Teacher | 1 | teacher1@example.com |
     And the following "courses" exist:
-      | fullname | shortname | format |
-      | Course 1 | C1 | topics |
-      | Course 2 | C2 | topics |
+      | fullname | shortname | format | groupmode |
+      | Course 1 | C1        | topics | 0 |
+      | Course 2 | C2        | topics | 1 |
     And the following "course enrolments" exist:
       | user | course | role |
       | student1 | C1 | student |
       | student2 | C1 | student |
       | teacher1 | C1 | editingteacher |
+      | teacher1 | C2 | editingteacher |
+      | student1 | C2 | student |
       | student3 | C2 | student |
     And the following config values are set as admin:
       | messaging | 1 |
@@ -79,6 +81,42 @@ Feature: Access to full profiles of users
     When I follow "Profile" in the user menu
     Then I should see "First access to site"
 
+  Scenario: View only shared groups in a course with separate groups forced
+    Given the following "groups" exist:
+      | name       | course | idnumber |
+      | Group 1    | C2     | G1       |
+      | Group 2    | C2     | G2       |
+    And the following "group members" exist:
+      | user     | group |
+      | student1 | G1    |
+      | student3 | G2    |
+      | teacher1 | G1    |
+      | teacher1 | G2    |
+    When I log in as "student3"
+    And I am on "Course 2" course homepage
+    And I navigate to course participants
+    And I follow "Teacher 1"
+    Then I should see "Group 2"
+    And I should not see "Group 1"
+
+  Scenario: View all groups in a course with visible groups
+    Given the following "groups" exist:
+      | name       | course | idnumber |
+      | Group 1    | C1     | G1       |
+      | Group 2    | C1     | G2       |
+    And the following "group members" exist:
+      | user     | group |
+      | student1 | G1    |
+      | student2 | G2    |
+      | teacher1 | G1    |
+      | teacher1 | G2    |
+    When I log in as "student1"
+    And I am on "Course 1" course homepage
+    And I navigate to course participants
+    And I follow "Teacher 1"
+    Then I should see "Group 1"
+    And I should see "Group 2"
+
   @javascript
   Scenario: Viewing full profiles of someone with the course contact role
     Given I log in as "admin"
@@ -96,6 +134,11 @@ Feature: Access to full profiles of users
     When I log in as "student1"
     And I open messaging
     And I search for "Student 3" in messaging
+    Then I should see "Student 3"
+    And I log out
+    When I log in as "student2"
+    And I open messaging
+    And I search for "Student 3" in messaging
     Then I should see "No results"
 
   @javascript
diff --git a/user/tests/externallib_test.php b/user/tests/externallib_test.php
index ba50e073324..df55cc4c18f 100644
--- a/user/tests/externallib_test.php
+++ b/user/tests/externallib_test.php
@@ -356,6 +356,12 @@ class externallib_test extends externallib_advanced_testcase {
         $this->getDataGenerator()->enrol_user($return->user2->id, $return->course->id, $return->roleid, 'manual');
         $this->getDataGenerator()->enrol_user($USER->id, $return->course->id, $return->roleid, 'manual');
 
+        $group1 = $this->getDataGenerator()->create_group(['courseid' => $return->course->id, 'name' => 'G1']);
+        $group2 = $this->getDataGenerator()->create_group(['courseid' => $return->course->id, 'name' => 'G2']);
+
+        groups_add_member($group1->id, $return->user1->id);
+        groups_add_member($group2->id, $return->user2->id);
+
         return $return;
     }
 
@@ -399,6 +405,9 @@ class externallib_test extends externallib_advanced_testcase {
 
         // We need to execute the return values cleaning process to simulate the web service server.
         $enrolledusers = \external_api::clean_returnvalue(core_user_external::get_course_user_profiles_returns(), $enrolledusers);
+        // Check we get the requested user and that is in a group.
+        $this->assertCount(1, $enrolledusers);
+        $this->assertCount(1, $enrolledusers[0]['groups']);
 
         foreach($enrolledusers as $enrolleduser) {
             if ($enrolleduser['username'] == $data->user1->username) {
diff --git a/user/tests/userlib_test.php b/user/tests/userlib_test.php
index 35b05d00227..67969ff99d6 100644
--- a/user/tests/userlib_test.php
+++ b/user/tests/userlib_test.php
@@ -912,4 +912,143 @@ class userlib_test extends \advanced_testcase {
         self::assertSame('5', $got['timezone']);
         self::assertSame('0', $got['mailformat']);
     }
+
+    /**
+     * Test user_get_user_details_permissions.
+     * @covers ::user_get_user_details
+     */
+    public function test_user_get_user_details_permissions() {
+        global $CFG;
+
+        $this->resetAfterTest();
+
+        // Create user and modify user profile.
+        $teacher = $this->getDataGenerator()->create_user();
+        $student1 = $this->getDataGenerator()->create_user(['idnumber' => 'user1id', 'city' => 'Barcelona', 'address' => 'BCN 1B']);
+        $student2 = $this->getDataGenerator()->create_user();
+        $student1fullname = fullname($student1);
+
+        $course = $this->getDataGenerator()->create_course();
+        $coursecontext = \context_course::instance($course->id);
+        $this->getDataGenerator()->enrol_user($teacher->id, $course->id);
+        $this->getDataGenerator()->enrol_user($student1->id, $course->id);
+        $this->getDataGenerator()->enrol_user($student2->id, $course->id);
+        $this->getDataGenerator()->role_assign('teacher', $teacher->id, $coursecontext->id);
+        $this->getDataGenerator()->role_assign('student', $student1->id, $coursecontext->id);
+        $this->getDataGenerator()->role_assign('student', $student2->id, $coursecontext->id);
+
+        accesslib_clear_all_caches_for_unit_testing();
+
+        // Get student details as a user with super system capabilities.
+        $result = user_get_user_details($student1, $course);
+        $this->assertEquals($student1->id, $result['id']);
+        $this->assertEquals($student1fullname, $result['fullname']);
+        $this->assertEquals($course->id, $result['enrolledcourses'][0]['id']);
+
+        $this->setUser($student2);
+
+        // Get student details with required fields.
+        $result = user_get_user_details($student1, $course, array('id', 'fullname', 'timezone', 'city', 'address', 'idnumber'));
+        $this->assertCount(4, $result); // Ensure address (never returned), idnumber (identity field) are not returned here.
+        $this->assertEquals($student1->id, $result['id']);
+        $this->assertEquals($student1fullname, $result['fullname']);
+        $this->assertEquals($student1->timezone, $result['timezone']);
+        $this->assertEquals($student1->city, $result['city']);
+
+        // Set new identity fields and hidden fields and try to retrieve them without permission.
+        $CFG->showuseridentity = $CFG->showuseridentity . ',idnumber';
+        $CFG->hiddenuserfields = 'city';
+        $result = user_get_user_details($student1, $course, array('id', 'fullname', 'timezone', 'city', 'address', 'idnumber'));
+        $this->assertCount(3, $result); // Ensure address, city and idnumber are not returned here.
+        $this->assertEquals($student1->id, $result['id']);
+        $this->assertEquals($student1fullname, $result['fullname']);
+        $this->assertEquals($student1->timezone, $result['timezone']);
+
+        // Now, teacher should have permission to see the idnumber and city fields.
+        $this->setUser($teacher);
+        $result = user_get_user_details($student1, $course, array('id', 'fullname', 'timezone', 'city', 'address', 'idnumber'));
+        $this->assertCount(5, $result); // Ensure address is not returned here.
+        $this->assertEquals($student1->id, $result['id']);
+        $this->assertEquals($student1fullname, $result['fullname']);
+        $this->assertEquals($student1->timezone, $result['timezone']);
+        $this->assertEquals($student1->idnumber, $result['idnumber']);
+        $this->assertEquals($student1->city, $result['city']);
+
+        // And admins can see anything.
+        $this->setAdminUser();
+        $result = user_get_user_details($student1, $course, array('id', 'fullname', 'timezone', 'city', 'address', 'idnumber'));
+        $this->assertCount(6, $result);
+        $this->assertEquals($student1->id, $result['id']);
+        $this->assertEquals($student1fullname, $result['fullname']);
+        $this->assertEquals($student1->timezone, $result['timezone']);
+        $this->assertEquals($student1->idnumber, $result['idnumber']);
+        $this->assertEquals($student1->city, $result['city']);
+        $this->assertEquals($student1->address, $result['address']);
+    }
+
+    /**
+     * Test user_get_user_details_groups.
+     * @covers ::user_get_user_details
+     */
+    public function test_user_get_user_details_groups() {
+        $this->resetAfterTest();
+
+        // Create user and modify user profile.
+        $teacher = $this->getDataGenerator()->create_user();
+        $student1 = $this->getDataGenerator()->create_user(['idnumber' => 'user1id', 'city' => 'Barcelona', 'address' => 'BCN 1B']);
+        $student2 = $this->getDataGenerator()->create_user();
+
+        $course = $this->getDataGenerator()->create_course();
+        $coursecontext = \context_course::instance($course->id);
+        $this->getDataGenerator()->enrol_user($teacher->id, $course->id);
+        $this->getDataGenerator()->enrol_user($student1->id, $course->id);
+        $this->getDataGenerator()->enrol_user($student2->id, $course->id);
+        $this->getDataGenerator()->role_assign('teacher', $teacher->id, $coursecontext->id);
+        $this->getDataGenerator()->role_assign('student', $student1->id, $coursecontext->id);
+        $this->getDataGenerator()->role_assign('student', $student2->id, $coursecontext->id);
+
+        $group1 = $this->getDataGenerator()->create_group(['courseid' => $course->id, 'name' => 'G1']);
+        $group2 = $this->getDataGenerator()->create_group(['courseid' => $course->id, 'name' => 'G2']);
+
+        // Each student in one group but teacher in two.
+        groups_add_member($group1->id, $student1->id);
+        groups_add_member($group1->id, $teacher->id);
+        groups_add_member($group2->id, $student2->id);
+        groups_add_member($group2->id, $teacher->id);
+
+        accesslib_clear_all_caches_for_unit_testing();
+
+        // A student can see other users groups when separate groups are not forced.
+        $this->setUser($student2);
+
+        // Get student details with groups.
+        $result = user_get_user_details($student1, $course, array('id', 'fullname', 'groups'));
+        $this->assertCount(3, $result);
+        $this->assertEquals($group1->id, $result['groups'][0]['id']);
+
+        // Teacher is in two different groups.
+        $result = user_get_user_details($teacher, $course, array('id', 'fullname', 'groups'));
+
+        // Order by group id.
+        usort($result['groups'], function($a, $b) {
+            return $a['id'] - $b['id'];
+        });
+
+        $this->assertCount(3, $result);
+        $this->assertCount(2, $result['groups']);
+        $this->assertEquals($group1->id, $result['groups'][0]['id']);
+        $this->assertEquals($group2->id, $result['groups'][1]['id']);
+
+        // Change to separate groups.
+        $course->groupmode = SEPARATEGROUPS;
+        $course->groupmodeforce = true;
+        update_course($course);
+
+        // Teacher is in two groups but I can only see the one shared with me.
+        $result = user_get_user_details($teacher, $course, array('id', 'fullname', 'groups'));
+
+        $this->assertCount(3, $result);
+        $this->assertCount(1, $result['groups']);
+        $this->assertEquals($group2->id, $result['groups'][0]['id']);
+    }
 }