I reported this problem too. Apparently, the issue is happening only when you try to enter in the main menu of pro clubs and you're a member of a club. If you are a "free agent", you can enter clubs. I guess the issue is only the main menu, because if you get a drop in invite and you directly accept it from the notifications, you can enter in the lobby and even play the match, but of course if you try to get back to the main menu you get the usual notification. Using this informations, i think we can all agree that the problem is pro club trying to load the rewards from the last season playoffs, so maybe EA can just cancel of all the last season rewards or cancel the little pop-up screen that you usually get at the end of the season. Probably this bug occurred because the game broke when the long-end game season ended the same day pro clubs playoff seasons ended.