On the IGES one, are you not rendering backfaces? Is it possible that the top surface was read in but needs to be flipped to point in the other direction?

For .obj, that is disappointing that MAX does not read NGons well. But you should get better results if you switch from ngons to Quads and triangles, or as a last resort just triangles only. That will leave less work for MAX to do on the import and will avoid the bug it appears to have when it tries to triangulate that complex ngon.

Please let me know if you still have problems.

- Michael