Michael
Not a very helpful couple of hours. I wont bore you with a lot of the other stuff.
I think, in the main, the problem relates somewhat (maybe/perhaps/inpart/also!!!) to the relationship between MoI and Carrara.

Here is that file you made exported as 3dm and obj from MoI.
!

Anyway, A shows problems in Carrara doing what I wanted to do.
B shows the same file as exported from MoI as an obj file.

MMmmmmnnmmm!

Brian