I was unaware tangents needed 4 elements. Do not remember if I just grabbed the first three or not. I know Blender is right handed, so if there were only 3, I have a 50 / 50 shot of adding just adding one. Not looking into it today.
If migrating to Blender 2.80 from MAX, you might also try using the glTF format as transport. Blender 2.80 has an importer, from Khronos, built right in. That combination might not result in split normals. As I described in the exporters approach of getting rid of UI to do flat shading for the 6.0 exporter, internally Blender either stores the type of normal (smooth or flat) on a vertex by vertex basis, or does custom split normals. Perhaps your case would resolve that way using that path.