So this is a Custom Rig I made a while back while this was a thing: Changing parts' transparency causes Deforming Models twitching
I returned just a few days ago discovered this bug was fixed! 
but sadly I found out my stuffs are bugging again. Here’s footage of the bug:
My character spawned in with no problem, his animations were running fine. Here’s his running animation, what it should look like:
But after I had him do this punching animation:
the stance of his running animation seems to be eased, not performing like how it should be, and not just the running animation, all other animations too, accept this one punching animation:
This was not happening before, seems like roblox did some update with how the animations work? Can anyone help me out with this? What is causing the problem exactly and how can I fix it?