I have been trying to save a customer envelope model as a STEP file, but the mass properties from the SLDPRT get overwritten when I save. When I open the STEP file again, it is seemingly an arbitrary mass, but not what it was when I saved. Similarly, if I overwrite the mass properties and save the SLDPRT as a CREO .prt, does anyone know if the mass properties would transfer over in that format?