The wings of flying mounts don't flap. You sort of just glide through the air gracefully. I'm not sure whether I actually dislike this bug. I think it's rather nice to not have the constant wing batting sound. And if you really want to see the wings move, just hover a bit. But I'm guessing they will get around to fixing it at some point.
(Thought I managed to get a pretty nice picture above there by the way, all color coordinated!)