MonstaMunch: He's unable to move because the game automatically gave me a queen, he would have been able to move if it had let me select a different piece instead.
I am sorry, but from the record, you never got a queen. With your last turn, you took his Rook with your own, your Pawn is still standing one field before the ground line.
From the system side, I can't really say anything what you are talking about, as it never happened. Your new promoted piece would have been next to JMich Rook. Whatever you have your pawn promoted to, he has taken it with his next turn.
The bugs with promotion are known (page 2 or 3 of this thread) and there is a workaround stated. The developer of the system is already looking into this, but this can take some time to be fixed.
If you are both fine with it, I can set up a rematch.
Please both keep in mind that promotion has some bugs.