Iray needs to be double precision

[SunDevilDave]

Yes, confirmed. We are working on a fix for this specific problem in iray.

That is awesome to hear. Thanks for your attention to this. I gather something must be happening when the mesh is tesselated at render time. If it was a true precision issue, I suspect we would be looking at an explode/imploded noisy mesh; but all the vertices of the box and mesh seem to be in the correct positions.

Thanks again,
Dave