AsRock B450M Steel Legend boots back to UEFI with CSM Disabled

[QuantumSingularity]

Ok guys, i tried to disable CSM on my mobo in order to enable Above 4G decoding and RE-Sizable BAR, something i did many times before on other similar boards, but this time it doesn't want to boot into Windows and brings me back straight to the main page of the UEFI w/o me pressing F2 or DEL. I tried disabling it, then enabling both option, then enabling CSM again, but when i boot into Windows, SAM on my RX 6900 XT is "unavailable". GPUz says that these option are disabled in BIOS. When i go back to BIOS they stay enabled, but they are grayed out like inactive options, until i disable CSM again. BIOS is the latest version and i have done this exact thing many times before on other B450 and B550 motherboards and never had any problem logging into Windows with CSM disabled. What is going on?

 

P.S

Ok i think i found out the culprit. For some reason my system drive is on MBR instead of GPT and for even weirder reasons, i can't convert it. Looks like another full system install is incoming

[heatonpkmassive]

Google it, there should be plenty of tools to convert to GPT without a full reinstall.