I think the problem with the new Wampa is that it’s a guy in a suit and he’s not a very good actor. And we see it far too much!
That and the mask is too dissimilar to the puppet utilized in the attack scene. I know there was discontinuity between the mask/puppet in the theatrical version, too, but there it’s a “blink and you’ll miss it” moment the casual viewer won’t notice. Here, we linger on the ugly mug long enough to notice the difference.