I have problems assigning groups to users when I use Groups Import Export. When I update groups, it works, but when I checked the users, the groups are not assigned.
I use BuddyPress in my site so I guessed it must be an incompatibility with groups and I deactivated. When active, I got errors while creating pages with assigned groups. When inactive, there are no errors creating pages and posts with groups. The problem seems to be not in the access limitation but on assigning the users.