I recommend clearing CMOS, booting into BIOS, and looking to see if there is an OC profile system.
If it exists, change the settings you want, and save it in 1 or 2 slots.
If any setting called BIOS Flash protection is available, enable it. I doubt it has ANY reference to the issue, but heck, why not.
reboot, go back into BIOS, and go back to OC profile, load it.
Reboot back into BIOS to verify it kept the settings.
sometimes just a CMOS clear is enough to fix random issues.
If you are feeling brave, you could flash an older BIOS (if currently at newest), reboot, and re-flash the newest/current BIOS. I dont think ASUS allows flashing the same/current BIOS over an existing version. If possible, I strongly suggest doing it with newest/current BIOS of course
BIOS flashing/reflashing is not 100% perfect, so I suspect it is a small chance of minor flash corruption
I am wary of touching BIOS flashing though, so be careful and patient if you choose this route.