Skinned Mesh Hum Root Problems and nonduplication of it's animation content

Ive run to a problem, never had these issues in past, Roblox completely changed how skinned meshes work and i’m really lost.

I export .FBX skinned mesh with animations inside of it, with wrongly positioned HumanoidRootPart

So i tried move the Root to my desired position, i removed all welding and reweld all splitted meshes back to its Root. And ive got this abomination. Note this was never happening to me ever, this is standard practice i was doing dealing with wrongly positioned Roots.

Complete limb elongation and distorted width after the procedure

And there is second problem, every time i duplicate a skinned mesh, with animations inside, the duplicated clone i CTRL PASTED doesn’t have them anymore. Again, this was never an issue in past.

I’m open to any suggestions, i need help. Really inconvenient.