That worked.
1. Uninstalled DA40NG
2. Moved all third party plugins
3. Reinstalled DA40NG
4. Ran X-Plane
5. Loaded aircraft
6. Registered aircraft with Gizmo
7. Verified RSG Diamond DA40NG menu is visible and accessible
8. Exited X-Plane
9. Moved back third party plugins
10. Repeated steps 4, 5 and 7 (2X) - All good.
Thanks for your help.