Hi zapum, is it possible for you to send me the STEP file? You can e-mail it to me at moi@moi3d.com . If it's very large you may need to use a file transfer service like Dropbox/OneDrive/etc... and send a link instead of a direct attachment.

I don't really know what might be going on without being able to test with the file, maybe the software that is generating your file has some kind of structure to it that MoI's translator is not expecting or something like that.

- Michael