Question Windows 10 installation error w/ ASRock AB350 Pro4

[nickolas_5122]

Hi.
I am installing Win. 10, 1909 - GPT(UEFI), my previously locatable boot options i.e. - (M.2/SSD/HDD) disappear once UEFI configuration is applied.-
However, two options remain; "UEFI SHELL...?" & "UEFI: SanDisk: Partition 1". The second option does boot but it displays an error: "Missing Media Drivers...".-
My question is: How can I enable the rest of my boot options whilst under UEFI config?
Thanks.

 

[punkncat]

Was this source (OS) disk in a system partitioned as MBR previously?

 

[nickolas_5122]

Was this source (OS) disk in a system partitioned as MBR previously?

Yes, I have had both partition scheme styles installed onto, and ran from this same device.(At one point or another...)

Also, my bootable USB which uses Rufus.ie, is partitioned in GPT, so with CSM: Off it should show?