The new user selector in the group admin page was filtering to only allow

selecting active users. This meant that if a group had existing users who had

been marked as inactive, trying to save any modifications to it would fail

until those users were removed. There's no good reason to do this, so I've

removed the filter from the field queryset.

Created a group with a few users and marked one of those users as inactive. Saw

that before the change, saving the group would fail, and after, it succeds.