Option Key Startup no longer works

Winclone
#1

I followed the step outlined in https://twocanoes.com/knowledge-base/migrating-windows-10-to-a-mac-pro-2019-with-winclone-8/.

At step 12 it looks like the install started, because of the “devices are getting ready” message, then the system rebooted to the black screen of death. After a reboot the Option Key startup drive option no longer works. Nothing I do seems to clear it. I’ve rebooted without the Windows external drive and FLASHDRIVE connected. now I’m completely stuck.

#2

I’ve verified that I have given full disk access to System Preferences inside the System Preferences >> Security & Privacy > Privacy tab and that Startup Security Utility Secure Boot is set to “No Security” and External Boot is set to “allow booting from an external device”

With further testing I’ve determined that if all external devices are removed that the Startup Manager (Option Key) works. Previously attempts to restore my PC’s Windows, I’ve been able to clear this issue with a complete Catalina reinstall. I really don’t want to do that again.
After selecting the MacSSD to boot at this point resolved the longer boot time issue that was also a side effect, but still no Startup Manager option with an external device attached. I’m going to try and toggle the security setting next.

It seems the Mac Pro 2019 guide is seriously flawed or I’m completely missing something.

#3

SUCCESS! It seems Reboot verse Shutdown and Power On make a big different in clearing this.

  1. Boot via the Recovery System (CMD+R)
  2. 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”
  3. Do a complete shutdown.
  4. Power on the Mac allowing the it to complete a full boot.
  5. Log in and then a shutdown.

The repeat the security setting process.

  1. Power the Mac on
  2. Boot via the Recovery System (CMD+R)
  3. 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”
  4. Do a complete shutdown.
  5. Power on the Mac allowing the it to complete a full boot.
  6. Log in and then a shutdown.
  7. 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.