Thanks for your reply. That is interesting. Followed your process, and it didn't work... until I rendered, then it fixed it. I suppose that is because the setting is a rendering instance engine setting?
Considering I only want this for an export to FBX and ultimatly to lumion, it's a bit of an odd fix, but it does indeed work. Is there not a way to fix the underlying geometry and reissue the railclone library object with it fixed? I would have thought that would be a more robust fix.
Thanks for the tips.