This is an issue that has been going on for quite a while, but wanted to see if anyone else is still having it?
Sometimes when accepting an invite to a group I only show myself. Or when inviting someone they don't see everyone else in the group or sometimes see a player or two with <NONAME>. Often times to get the group window to sync with everyone, we have to kick/invite/kick/invite two or three times. Also, promotes don't always work. An individual is promoted but on their group window they are not. Once again kick and reinvite until it syncs.