Group admin can see users not in group

I recently upgraded to 30.0.7 and just had a group admin let me know that he can see all the users in the instance…not just the ones in his group. I don’t think he can edit them, but they should not be visible.

How do I fix this? This is definitely not the desired behaviour and I need to add new groups (and admins) that do not have visibility to one another.