When a user is unenrolled from a Canvas course, then re-enrolled, Canvas restores most previous settings and progress for the user in that course (grades, discussion posts, assignment submissions, quiz activity, etc.). It should restore all settings and progress, including group enrollments for that student, as well as any enrollment into Assignment "Assign to" settings (differentiated assignments). The use case is this--in the event that a large group of students are unenrolled, it is catastrophic to instructors and students if those settings and enrollments are lost. In fact, when differentiated assignment settings are lost for past assignments, the grades are no longer in the course for that student who took that quiz or assignment.
When a student is re-enrolled into a Canvas course, after being unenrolled, Canvas should restore all settings, activities, enrollments, etc. for that student, including groups and differentiated assignments enrollments.
