Moi flipping polygons on export.

 From:  PaQ
4531.4 
Hi Andy,

If you are using .obj to export geomtry into modo, you can have troubles with ngones badly triangulated, and some faces can be flipped.

Complete reversed surfaces can happend with non solid geometry like Burr discribe.

Pay attention that MoI creates double side surfaces automatically for single surfaces when using .lwo (check the modo shader tree)

That's maybe why the object looks right using this format.