Editing a page removes section assignments

After editing a page from My Sections and submitting it, the section definitions within the menu disappear.
This means that every time someone edits a page, I have to redefine all the sections in the menu, and then assign each section to a user again.

It happens immediately after pressing the save button. To make sure it was not any other modules, I removed modr8 and Revision Moderation, and returned settings to their originals, but it still happens.