Good luck m8.

Well obvoiusly the issue lies with the hoopShape geometry in the scene (which is the helix shaped object).

Maybe it was the way that Motion Blur that has been added to the scene. TBH, I think it was the way the geo was created that caused this warning. I take it motion blur was required for the project?

The only other way around it would have been to render 2 images, one in MR and one as a SW render and composite.

I have had a look on the web and the error you report only seems to point to an issue with MR and Motion Blur on certain bits of geo. I take it you did the basics of deleting history on the objects, before to did the convertion?