Why does Canvas reassign to everyone a differentiated assignment if I edit it?

[lcarney]

In a cross-listed course, one instructor differentiates all her assignments to one section or  the other of students in her course.  When assigning to that section, Canvas will ask if she wants to continue to assign it to just that section, and she clicks on continue.  That is fine, but what is troublesome is when the instructor goes back to that assignment or quiz, and makes any edits and then re-saves it, Canvas automatically reassigns it to everyone in the course without any warning.  We have to remember to go back in and x out "everyone", so that only the one section is assigned.  Is there a way to fix this?