Oh, I see. Skinned meshes don't behave correctly anymore when scaled inside Babylon.js.
It appears I can fix this by using a transform node instead of scaling the model directly. Which I'm looking to add to the next update planned for later this month.
If you want to circumvent the issue for the time being you can add "scene.skipFrustumClipping = true;" at around line 376 in the runtime.js file of the main plugin.