For those following this post, I sent Michael the .sat file for one of the windows in the project, as well as the .rfa file created by the window manufacturer selected for the project.

Michael@ "But if Revit has created a single brep made up of disjoint faces, then MoI is just reading in what Revit has generated". Yes, I agree, that makes sense to me. But these are not disjoint FACES, it is a "double solid" of sorts.

If anyone knows how to make a "double solid" in MoI3D like the one I posted above, please explain to me how to do it. And I think Santa Claus will give him the gift of his dreams!