Can't Join Friends In Game

Got an invite from a friend to play. Hit accept, and now I'm sitting in the main menu with the message "Waiting for leader" (if i hit PLAY) but otherwise I just SIT here, while they're all still in a game. (it's checkpoint, so I really see no reason why I can't join)

Had to wait for their damn game to finish... ugh

@amurka
that means the ivites are not working for game yet.
and as you may know, you will have to wait till the party leader joins a new match.