Hey Mike,
Ah thank you for explaining, unfortunately, I don't have any experience with going GIS to CAD so this might be something to put a post up on any forms relating to your CAD software.
If the hatch is showing fine within ArcGIS then it might be a defect or limitation of the CAD software, so if possible I would test this on different platforms.
Sorry I couldn't help further on this,
David
Esri UK -Technical Support Analyst