I'm not quite sure if this is a bug or not, but if you leave the screen of the mobs you provoked they will stop fighting. Also for example if there is a lich, a mummy, and a wraith. If i provoke the lich onto the mummy and the wraith onto the lich, after the lich kills the mummy it will immediately attack me instead of attacking the wraith who is the one dealing damage to the lich. Not sure if you feel me but I'm just not use to it working this way.