Studio keeps messing with my custom character

Sup. I am meant to finish a horror game by June 1st. The game is almost finished all I had to do was add a few more animations to the main ‘‘monster’’ for the game.

The problem is that a lot of the time when I open animation and try to animate said character it just completely messes up the character and destroys most of the welds and joints (Very annoying). The character has a lot of body parts so it takes a very long time to re-rig it only for it to break after a few days.

This is the dude we’re talking about:

BY THE WAY the fella looks completely fine before I open the animation editor. The moment I open the editor it not only messes up the animation but it changes the humanoid to the way it was in the editor

And this is what studio does to the poor guy when I open animation editor:

robloxapp-20230530-2109309.wmv (1.0 MB)

The way he looks like in the animation editor will stay like that even if he’s outside the editor.

Help