When on a course, the $PAGE->user_is_editing is called in various places and the way the capabilities are checked are different if it is a full page refresh or a single item refresh (for example a section) leading in a different layout (menu absent) when doing a partial refresh.

This is working fine for teacher who have by default the following capabilities:

• moodle/site:manageblocks
• moodle/course:setcurrentsection

This was revealed by the test created for MDL-81335.

To reproduce:

As admin create new role specialteacher with archetype teacher on course context and remove the following capabilities from the role:

• moodle/site:manageblocks
• moodle/course:setcurrentsection

Then:

• Create a new course with at least two sections and one activity
• Enrol a user with role specialteacher
• Log in as this user and open the course.
• Enable Edit mode.
• Hide a section
• Show a section again
• You will notice that the hamburger menu is missing in the section card
• Reload the page
• You will see that the hamburger menu is back

This is, I believe because in the course/view.php we set the other capabilities and we do not do it in the AJAX/reactive routine.