A few games ago (didn't note game number, unfortunately, but it was probably Monday or Tuesday this week if there are logs available) I found I was simply unable to play the Coin of the Realm card from my hand, i.e., in the buy phase. When I clicked on it to play it then all other buttons (i.e., end turn, buy cards) either disappeared or failed to appear such that I could not do anything else. It didn't interfere with the chat with my live opponent, and I could Undo without problem. It happened multiple times in the same game, i.e., every time I tried to play CotR from my hand then the same bug would occur. Not playing it allowed the game to proceed fine in other respects. I've had other games where CotR worked as it should, so I'm not sure what it was interacting with to produce this bug.