Hi @Hawx , I don’t believe that this is a bug.
Unlike the active player, the defender in a PvP match is treated like a PvE match where the opponent cycles through two abilities.
When setting up a PvP defense, the player can actively choose the two abilities to use in the PvP defense. These abilities are not those from the class itself, but are from pets that are equipped to the defending unit. If the defending player has no pets equipped in their PvP defense setup, there are no abilities for the AI to use in the match. That results in exactly what you are observing.