Weird problem. Looks as if subparts (or primitives!) are somehow rendered separately.
I think you made a wrong manipulation for inlining, here it works perfectly.
In the following image, left is a triangle soup (deep inlining), middle uses 1-8sphe primitives, right uses 4 subparts with inner/outer skin.
Studio POV render looks good:
I think you made a wrong manipulation for inlining, here it works perfectly.
In the following image, left is a triangle soup (deep inlining), middle uses 1-8sphe primitives, right uses 4 subparts with inner/outer skin.
Studio POV render looks good: