Nostalrius Begins - Quality wow vanilla realm (1.12)

When I get invited to a guild the prompt comes up if I want to accept or not. When I click accept the prompt goes away but it is as if I did not accepted. Guild tab in the social menu is grayed out. Cant talk in guild chat. /gquit tells me I am not in a guild. The inviter is telling me he gets the message "already been invited to guild"

Things I've tried:
* Relogging
* /reload UI
* not playing then trying again after a few hours
* Deleting WDB folder

Turns out one, or more of the guilds I tried to join may have been full. Will update later.