NPC enemy is frozen in studio, but isn't anchored, help?

Hi, I'm not sure if I can get help for this here, but I can't use the dev forum just yet. i've been working on making a newer model for a monster in one of my games. (I'm using some Roblox-made body parts for it) When I go to test it in studio, to make sure he's moving around correctly, he is able to idle but he is stuck in the same place. If I'm allowed to, I could link a video to a screen recording I took to better explain what he's doing.

He doesn't have any part welded to the baseplate, but he DOES have weld constraints because it's the only way I was able to keep his arms attached to his body. I think that might be the issue, but i'm unsure, and like I said it is the only way i've found to keep his limbs attached to his body. I have his old model in the same place, and that model is able to move around just fine. (the only weld constraints he has is to attach some details, not full limbs)

If he's frozen because of the weld constraints, I'm not sure what to do to keep his limbs attached to his body without using those.

Don't test through studio test through Roblox. Also for the leg part your going to maybe need to fix the animation or something.