diff --git a/grade/edit/tree/item.php b/grade/edit/tree/item.php
index 64ddf7f7d8c..45757d25377 100644
--- a/grade/edit/tree/item.php
+++ b/grade/edit/tree/item.php
@@ -190,7 +190,7 @@ if ($mform->is_cancelled()) {
 
     if ($item->cancontrolvisibility) {
         // Update hiding flag.
-        $gradeitem->set_hidden($hide, false);
+        $gradeitem->set_hidden($hide, true);
     }
 
     $gradeitem->set_locktime($locktime); // Locktime first - it might be removed when unlocking.
diff --git a/grade/edit/tree/lib.php b/grade/edit/tree/lib.php
index bcc79b43822..8e1be55d653 100644
--- a/grade/edit/tree/lib.php
+++ b/grade/edit/tree/lib.php
@@ -683,11 +683,15 @@ class grade_edit_tree {
                 $gradeitem->grademin, $gradeitem->grademax, 'gradebook');
         }
 
-        // Update hiding flag.
-        if ($hiddenuntil) {
-            $gradeitem->set_hidden($hiddenuntil, false);
-        } else {
-            $gradeitem->set_hidden($hidden, false);
+        // Only update the category's 'hidden' status if it has changed. Leaving a category as 'unhidden' (checkbox left
+        // unmarked) and submitting the form without this conditional check will result in displaying any grade items that
+        // are in the category, including those that were previously 'hidden'.
+        if (($gradecategory->get_hidden() != $hiddenuntil) || ($gradecategory->get_hidden() != $hidden)) {
+            if ($hiddenuntil) {
+                $gradecategory->set_hidden($hiddenuntil, true);
+            } else {
+                $gradecategory->set_hidden($hidden, true);
+            }
         }
 
         $gradeitem->set_locktime($locktime); // Locktime first - it might be removed when unlocking.
diff --git a/grade/tests/behat/grade_item_form_unhide.feature b/grade/tests/behat/grade_item_form_unhide.feature
new file mode 100644
index 00000000000..f0680033ed6
--- /dev/null
+++ b/grade/tests/behat/grade_item_form_unhide.feature
@@ -0,0 +1,123 @@
+@core @core_grades
+Feature: Teacher can unhide grades on the edit page allowing students to view their grades
+  In order to show the grades of an activity to a student
+  As a teacher
+  I need to unhide an activity on the edit page
+
+  Background:
+    Given the following "courses" exist:
+      | fullname | shortname | category |
+      | Course 1 | C1        | 0        |
+    And the following "users" exist:
+      | username | firstname | lastname | email                |
+      | teacher1 | Teacher   | 1        | teacher1@example.com |
+      | student1 | Student   | 1        | student1@example.com |
+    And the following "course enrolments" exist:
+      | user     | course | role           |
+      | teacher1 | C1     | editingteacher |
+      | student1 | C1     | student        |
+    And the following "activities" exist:
+      | activity | course | idnumber | name                 | intro                       | assignfeedback_comments_enabled |
+      | assign   | C1     | assign1  | Test assignment name | Test assignment description | 1                               |
+    And I am on the "Test assignment name" "assign activity" page logged in as teacher1
+    And I navigate to "View all submissions" in current page administration
+    And I click on "Grade" "link" in the "Student 1" "table_row"
+    And I set the following fields to these values:
+      | Grade out of 100  | 50                       |
+      | Feedback comments | I'm the teacher feedback |
+    And I press "Save changes"
+    And I am on "Course 1" course homepage
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    And I should see "50.00"
+    And I should see "I'm the teacher feedback" in the "Feedback comments" "table_row"
+    And I log out
+    And I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I navigate to "Setup > Gradebook setup" in the course gradebook
+
+  @javascript
+  Scenario: Hiding the activity using the drop-down hide link and then unhiding the activity using the edit settings form page
+    Given I click on "Edit" "link" in the "Test assignment name" "table_row"
+    And I click on "Hide" "link" in the "Test assignment name" "table_row"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    And I should not see "50.00"
+    And I should not see "I'm the teacher feedback"
+    And I log out
+    And I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I navigate to "Setup > Gradebook setup" in the course gradebook
+    And I click on "Edit" "link" in the "Test assignment name" "table_row"
+    And I click on "Edit settings" "link" in the "Test assignment name" "table_row"
+    And the field "Hidden" matches value "1"
+    And I set the field "Hidden" to "0"
+    And I press "Save changes"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    Then I should see "50.00"
+    And I should see "I'm the teacher feedback" in the "Feedback comments" "table_row"
+
+  @javascript
+  Scenario: Hiding the activity using the edit settings form page and then unhiding the activity using the drop-down show link
+    Given I click on "Edit" "link" in the "Test assignment name" "table_row"
+    And I click on "Edit settings" "link" in the "Test assignment name" "table_row"
+    And I set the field "Hidden" to "1"
+    And I press "Save changes"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    And I should not see "50.00"
+    And I should not see "I'm the teacher feedback"
+    And I log out
+    And I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I navigate to "Setup > Gradebook setup" in the course gradebook
+    And I click on "Edit" "link" in the "Test assignment name" "table_row"
+    And I click on "Show" "link" in the "Test assignment name" "table_row"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    Then I should see "50.00"
+    And I should see "I'm the teacher feedback" in the "Feedback comments" "table_row"
+
+  @javascript
+  Scenario: Hiding the category using the drop-down hide link and then unhiding the category using the edit settings form page
+    Given I click on "Edit" "link" in the "Course 1" "table_row"
+    And I click on "Hide" "link" in the "Course 1" "table_row"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    And I should not see "50.00"
+    And I should not see "I'm the teacher feedback"
+    And I log out
+    And I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I navigate to "Setup > Gradebook setup" in the course gradebook
+    And I click on "Edit" "link" in the "Course 1" "table_row"
+    And I click on "Edit settings" "link" in the "Course 1" "table_row"
+    And the field "Hidden" matches value "1"
+    And I set the field "Hidden" to "0"
+    And I press "Save changes"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    Then I should see "50.00"
+    And I should see "I'm the teacher feedback" in the "Feedback comments" "table_row"
+
+  @javascript
+  Scenario: Hiding the category using the edit settings form page and then unhiding the category using the drop-down show link
+    Given I click on "Edit" "link" in the "Course 1" "table_row"
+    And I click on "Edit settings" "link" in the "Course 1" "table_row"
+    And I set the field "Hidden" to "1"
+    And I press "Save changes"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    And I should not see "50.00"
+    And I should not see "I'm the teacher feedback"
+    And I log out
+    And I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I navigate to "Setup > Gradebook setup" in the course gradebook
+    And I click on "Edit" "link" in the "Course 1" "table_row"
+    And I click on "Show" "link" in the "Course 1" "table_row"
+    And I log out
+    And I am on the "Test assignment name" "assign activity" page logged in as student1
+    Then I should see "50.00"
+    And I should see "I'm the teacher feedback" in the "Feedback comments" "table_row"
diff --git a/grade/tests/external/create_gradecategories_test.php b/grade/tests/external/create_gradecategories_test.php
index dfde44b8e5f..553df7c71c3 100644
--- a/grade/tests/external/create_gradecategories_test.php
+++ b/grade/tests/external/create_gradecategories_test.php
@@ -85,7 +85,7 @@ class create_gradecategories_testcase extends \externallib_advanced_testcase {
             'display' => GRADE_DISPLAY_TYPE_LETTER,
             // Hack. This must be -2 to use the default setting.
             'decimals' => 3,
-            'hiddenuntil' => time(),
+            'hiddenuntil' => 0,
             'locktime' => time(),
             'weightoverride' => 1,
             'aggregationcoef2' => 20,
diff --git a/lib/tests/grades_externallib_test.php b/lib/tests/grades_externallib_test.php
index 01807e63e51..b0a5e33b45c 100644
--- a/lib/tests/grades_externallib_test.php
+++ b/lib/tests/grades_externallib_test.php
@@ -579,7 +579,7 @@ class core_grades_external_testcase extends externallib_advanced_testcase {
             'display' => GRADE_DISPLAY_TYPE_LETTER,
             // Hack. This must be -2 to use the default setting.
             'decimals' => 3,
-            'hiddenuntil' => time(),
+            'hiddenuntil' => 0,
             'locktime' => time(),
             'weightoverride' => 1,
             'aggregationcoef2' => 20,