Now...I am not sure about Max 7 ( I use 6 ) but I haveonly ever had models that open properly, or don't open at all due to being 'old versions' which the game doesn't seem to use.

I am wondering if you are looking at models with a 'gloss' texture. This gives some of the units shiny armour. It would possible make for a black display. Just guessing here... I never actually had that happen to me!!!