Weird bug -- Sapphire Yak displays wrong attack value

In my game against dabestaround that just ended, I had a few Sapphire Yaks on the board and collected with one of them. It was supposed to become a 16/18 but only showed as a 12/18:

when I attacked the orb, it did 16 damage, still showing as a 12 attack creature:

I think I saw this in a game too. Gameplay is fine, but visual bug.