Desperate for a solution to defend myself against a Shard of Patience attack vs multiple water mobs, I placed "Enchant Artifact" on his Shard of Patience, hoping that this might make it impossible to cancel, thus preventing all his water creatures from ever attacking me.
It didn't work, and the shard was cancelled the next turn.
The bug, though, happened when the Shard was played again, because it was also Enchanted. Whether this was a graphical bug or not, I was unable to confirm.