MTG Arena game locked due to Graaz, Unstoppable Juggernaut, and Oko, Lord of the Fae mechanics. Played Graaz while Oko was on the board; was forced to attack but couldn't due to Oko. Board state in the screenshot. Don't know if the game saw the ornithopter (which was also forced to attack due to Graaz) and thought I had mana available, but at this state i could only declare him as an attacker and don't tap him for mana. Tried to press "No Attacks" didn't do anything. Tried to skip all actions and end turn, didnt do anything.
Edit: While writing this, another idea came to my mind - switching to full control mode and trying to tap the Ornithopter. Havent tested this.