Strange Ragdoll Physics

Does anybody have any idea what might cause a ragdoll to simply “crumple” in mid-air and freezing it in place?
It’s sort of hard to explain, so i took a screenshot. The physics asset I’m using doesn’t do this when I simulate physics, and i cant find any weird collisions with their weapons or anything… any ideas?

Hi,

Might be wrong, but have you re-imported them with the the skeleton you need?

Regards