My fighter was attacked by a Predictable stab from one of two Trog Scuttler sharing one deck. The fighter blocked the attack with an Icy Block, killing the attacking Scuttler (1/7) because of the 3 pearcing damage from the blocked stab. The maximised Icy Block stayed at the center of the screen. Well, i played a Flame spirit, attacking a Trog Spearman, but the card stayed on screen. The remaining Scuttler played a Scuttle and moved. At that moment the Icy Block shrinked and attached to that creature.
PS: Next round, the Icy block is still attached to the Scuttler, but he seemed to be able to move alt least one field whit a scuttle (Scuttle (Free move) 2 - Icy Block (Encumber) 2 ) = 0 < 1
The exact same thing happened to me today. It seems to be a bug when a succesful roll with icy block makes the attacker die (as with Predictible Stab). The Icy Block card stays in the middle of the screen, and when another opponent's character plays a move card it attaches to him, although it doesn't have real consequences because he is able to move as he doesn't have the Icy Block attached.
I've once had something like this in SP, went away after a few cards were played, can't remember anything more.