My suggestion would be to delete your local copy of the Lich Hound and drag one in fresh. If somehow the token image has been deleted, no amount of dragging in a new one will fix the issue. Roll20 looks and says, "Ah, you already have a lich hound in your game. I don't want to overwrite any changes you might have made, so instead of dragging from the Compendium, I will drag in a fresh copy of you local instance." Of course, if you do this and there is still a problem, there might be a larger issue.