Fullbacks( DL, DL/DC, DR, DR/DC or DL/DC/DR) cannot assist from the wings except for the set piece. It's not possible at the moment, it's 100% broken. You can monitor the bug from the same copy/paste ****ty animations all passes going out without exception.
What's the point of developing fullback's cross passing skills when you can't call this game as a football game? Sorry i cannot do this while a fullback isn't doing anything in the game.