So we have times when courses (such as Honors and Non-Honors) are combined into one course and divided by section. There are also times when students assigned to one section will be moved to another but rather than delete them outright from the previous section, we have been testing just doing 'conclude enrollment' for the section we no longer want them to access.
While this allows their grades for both sections to appear in the gradebook, it also seems to allow them to continue viewing and submitting for the section we concluded their enrollment in. I can't seem to find any documentation regarding if this is working as Instructure intended or a bug.
We don't typically "conclude" enrollments (we have term dates set to end access), but we've seen the similar behavior when there are two sections in a course and a student drops one and gets marked "inactive", then enrolls in the other section. We've reported it to Instructure, but as far as I know it's a bug that hasn't been fixed.