Custom rig (dinosaur) unable to move on anything that isn't flat

I imported a rigged Dinosaur (with bones) into studio, and while the animations work fine, the Dinosaur can’t seem to go on anything that isn’t flat.

Note: The bodyparts are one mesh only.

Some solutions I tried:
I tried increasing the hipheight of the humanoid, but the Dinosaur just floats above ground
I tried seperating the parts (tail, torso, head, legs) but same issue.

Video of what is happening:

Rig’s children & humanoid properties: