Xantcha caused lost priority in an EDH game

An opponent before me plays Xantcha (from his command zone), gives it to the player opposite of him. Xantcha is forced to attack during that player's next turn. When that player's turn comes up again, he casts a boardwipe and Xantcha goes back to its owner's command zone.

Xantcha player casts Xantcha again, giving it to me (my turn directly after his). During my turn, when I enter the attack step, priority gets lost as I can't choose a person to attack. "/fix" says that Xantcha's owner has priority, but he can't do anything either. We rolled back successfully, but priority was still lost.