I doubt that is the trouble (They did get installed into separate folders for V12 and V16, right?)
I have V9, 10, 11, 12, 13, 15 and 16 installed and they all seem to run.
I'm doubtful about that too but it's easy to test. Copy some models (and any bitmaps or other assets they need) to your regular drive and see what happens.
Definitely, even aside from A:M.