Posted by https://github.com/KyeDuo

with smart moving: (prob smart render/render player API/Render player API enhanced)
the mannequin's body goes nuts if the head is left with the orientation of 0,0,0.
Moving any head orientation off zero will fix this issue.
Prob not your end, but SM will not respect the restrict limb movements option. I have let SM know of this issue.

Presuming this is fixed.