B760 PRO RS Secure Boot Key missing

You will probably need to open a support ticket for this issue. There is nothing
I can do to help you, I am just a moderator here. ASRock does reply here sometimes
but it's not very regular so a support ticket will be a quicker way to get the answer
you are looking for.

http://tw.asrock.com/events/tsd.asp

That is strange. Have you tried the following:

1. Open PowerShell as Administrator
2. Enter the following command to check your certificate status:

[System.Text.Encoding]::ASCII.GetString((Get-SecureBootUEFI db).bytes) -match 'Windows UEFI CA 2023'

3. If the result is an error (variable undefined) then enter this:

reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Secureboot /v AvailableUpdates /t REG_DWORD /d 0x5944 /f

4. Then enter:

Start-ScheduledTask -TaskName "\Microsoft\Windows\PI\Secure-Boot-Update"

5. Restart the system and then enter PowerShell as administrator again.
6. Reenter the command from 2 and you should see "True" confirming the update has been applied.

Let me know if it works.

Edited by Xaltar - 54 minutes ago at 2:00pm