SUCCESS! It seems Reboot verse Shutdown and Power On make a big different in clearing this.
- Boot via the Recovery System (CMD+R)
- Then toggle the security settings using Startup Security Utility Secure Boot setting it to “Full Security” and External Boot is set to “Disallow booting from an external device”
- Do a complete shutdown.
- Power on the Mac allowing the it to complete a full boot.
- Log in and then a shutdown.
The repeat the security setting process.
- Power the Mac on
- Boot via the Recovery System (CMD+R)
- Then toggle the security settings using Startup Security Utility Secure Boot set to “No Security” and External Boot to “allow booting from an external device”
- Do a complete shutdown.
- Power on the Mac allowing the it to complete a full boot.
- Log in and then a shutdown.
- Power on the Mac and press the CMD key and the available boot devices now appear.
I’m not sure if logging in is required, verse just shutdown from the login screen, but this sequence clear the problem. However, now I’m wondering if the issue here all a long was reboot verse restart.
Now I’m back to my restoring my PC image to BootCamp problems.