Here is the screen shot.

http://imgur.com/a/oz786

This happens when I play Night terror sometimes. I draw 5 cards but then suddenly one of them disappeared. When it happens, I must play with just 4 cards until the end though in fact I have 5 in hands, one of them is just invisible and can't be played (I know because Terrifik created 3 Sarcastic Laugh even though I saw only 2 hand difference).

I feel like this bug used to happen before too. If I remember correctly, it's with N'taba Circus deck.