FBX import issues

A Problem I've been experiencing is when using FBX format.
Generally when combining multiple objects, or seemingly when saving-closing Maya- then reopening.
what would happen is that any sections that were created via duplication would completely lose their UVs:

 The image here, has the same material  on everything, yet parts of it are showing up white.
This is because their UVs have disappeared completely...
after spending many days, of reopening the FBX, re UVing etc, I couldn't work out what the exact cause of the issue was, so in the end I had the model as separate objects, then selected the whole thing, and exported as OBJ, which seems to have fixed it.