Cannot enter conditional moves

In one of my games (http://www.chess.com/echess/game?id=77142840) I am not able to enter conditional moves.

After the conditional moves board appears I am not able to enter opponent's valid move - white pieces cannot be dragged.

Is this because the game is chess 960? I never experienced problems with conditional moves in normal chess.

Edit: I had no problems in another 960 game so this is something else with this particular game which prevents me from making a conditional line

Sorry you're having troubles! Can you please try a cache clear to see if that helps at all?

I have just finished that game, in another I have no problems with conditional moves.

Thanks for the hint, it might be useful next time I experience malfunction