I noticed this happening after changing my username to one with an underscore (El_Capitan). When someone accepts me into a group, it doesn’t actually accept me. The group says that I’m in, but on my side, it shows the page you get when your not in a group.
EDIT: It has put me in now, just a weird caching error maybe.
Quick follow-up question: Is this still happening? I ran into this once but it went after a while (by a while I mean a couple of minute). It could be a cache issue – did you try full refreshing the page?
Yeah - this isn’t new, sometimes it will say you’re in the group but as the rank “Guest” (using :GetRankInGroup() and :GetRoleInGroup() will return 0 and “Guest” respectively too). This fixes itself over time.