- Joined
- Jun 26, 2012
- Messages
- 4,069
- Motherboard
- Asus Z170 Deluxe
- CPU
- i5-6600K
- Graphics
- GTX 970
- Mac
- Mobile Phone
You could test deleting those keys and see what affect it has on your macOS Sierra drive boot option in the BIOS. The only thing that has changed since downgrading your BIOS is that is it been reset. Check under CSM as you have the option to use both Legacy and/or UEFI boot devices with priority. I have the Secure Keys deleted in my BIOS.Interestingly, in the secure boot setting I have it set as 'other os' but the secure boot state above says 'enabled'. Is it worth clearing the secure boot keys or something like that?
You could reset the CMOS too and see if that boot option reappears.