After joining a different League, a player temporarily cannot score points for their new League in the ongoing League Tournaments. Once the player successfully finishes a 7-day period, they can participate and score points in the next League Tournaments to help their League succeed.
Sometimes, you can get bad timing when your 7-day probation ends hours or even minutes before the League Tournament starts. Unfortunately, in this case, new League Members will still be unable to participate in the soon-to-be-launched League Tournament.