Well that's really amazing! I have a similar thing happening in the above render. there should be at least a little reflected light along the top right edge of the wall from all the light outside. Maybe since it is an original rhino nurbs, it is seeing (and getting light blocking somehow) part of the surface that the control points tell us are still there in Rhino??? Who knows? Then there is another Rhino import that I have where the light spills in through a booleaned opening.....