Ok it probably does happen in the default UI as well as Profit but you'll only really see it occur while using Profit simply because Profit allows you to click accept while your character is still loading in.
Quite simply if you accept a group/raid invite while your character is still loading into the game the group window shows "Group Member" instead of class name etc etc. Although it does corect itself the next time you load into a new zone or for any other reason.
The fix is easy tbh, just wait until you're fully in game before you accept the group invite and away you go...no more problem
