I don't have Ryzen Master but could it be that your Motherboard BIOS doesn't support or is configured to run in UEFI mode only instead of UEFI/LEGACY Mode?
Look in BIOS and see if it has a UEFI/Legacy Mode setting. If it is set for UEFI only see if you set it to UEFI/Legacy Mode and then see if Ryzen Master than has that switch available.
Or maybe Ryzen CPU is not compatible in the Legacy Mode. Someone else will need to assist with this. I am just guessing at the moment.