There is a problem with the final Morganthe battle since the game was updated last week. I have been farming it daily and once we get inside the room, one person clicks through the messages. By the time they are done, Morganthe automatically pulls one random person into battle. It has happened every time.
The problem with this is that sometimes the person Morganthe chooses is still fixing their deck. Sometimes, the person didn't mean to tank. Sometimes others in the room are not fast enough to join the battle and the person is alone.
I have seen people flee and use the Recall button because they didn't want to be targeted. If you actually want that first spot, you're unable to get it because Morganthe makes that decision by pulling in a random person.