I am having this problem as well. I have narrowed it down to something with the parent of the head of the fixture. Something with the pivot point there. The pivot point of the mesh itself is correct but something in the DMX controlled ‘head’ component isn’t lined up correctly. Any ideas?
EDIT: Solved this. I had the mesh higher than the ‘Head’ component. I simply set the mesh location transform z axis to ‘0’ and adjusted the ‘head’ component location transform to the correct z axis height.