There’s nothing wrong with the STEP file from Rhino. Solidworks, Fusion, Rhino, and others have no problem reading it. In STEP, there are many, many ways to represent the same thing. The Rhino STEP file is pretty much the same as the one from Fusion with several minor differences in the way things are represented. The Tailor product must be written to understand the STEP files from Fusion but there’s something it doesn’t understand from ours. We come across similar situations with our importer every now and then, even after 20 years. I just figure out what entities our reader doesn’t understand and write the code to deal with them. No doubt the same holds for TailorSteel. I’ve submitted a request for someone there to contact me about this. Hopefully we can figure out what’s going on.