export to CGM Binary 4 does not support Bezier curves - why?

Exporting to CGM Binary 3 supports all my curves.  But a recent problem with our viewer has me using Version 4.

But exporting to Version 4 Binary does not support Bezier Curves - why? I need this to work. When I export to Version 4, the Bezier curves are jagged, not smooth as they were in Version 3.

If I didn't have to use CGMs, I wouldn't. But I have to, which is the bain of my existence.