Non-Reproducible
This issue was not reproducible when tested by the development team. Issues may be given this status when they cannot be reproduced or are no longer relevant in a development version of the software, but a specific fix was not installed to address the issue. The issue's Additional Information section may contain further explanation.
Additional Information
No Public Explanation
Workaround
Export the shapefile to a .dgn then save as .dwg in AutoCAD or use the Quick Export tool via the Data Interoperability Tools.