My opponent in the game #141797409 on tokyo last evening (US central time) was unable to play a Bounty Hunter using Captain's ability. The problem was fixed neither by his logging out and logging in again, nor by undoing the play of the Captain and playing it again anew after having logged out and back in.
Thanks for the report, Megas_Droungarios! I found the correct game (141798032) and assuming your opponent resigned at this time, I'm at a loss to explain what happened. When I load the game at the end I can play Captain and can choose to play Bounty Hunter with it without any problem.