Try re-importing this into NX and check the result there.
If it's fine then you maybe should ask the Solid Works forum for help.
All neutral files like Step, IFC, Iges ( and DXF/DWG ) are translated 2 times, #1 by the exporter and #2 by the importer.
Regards,
Tomas
The more you know about a subject, the more you know how little you know about that subject.