AMD's documentation on this is less than stellar. While I do not have a direct answer for you I can share how I got NVME & SATA Raid working after days of research and time dealing with ASUS & AMD.
The Best Doc: https://drivers.amd.com/relnotes/amd-raidxpert2_user_guide.pdf
Driver Selected: NVME_DID
1st rcbottom
2nd rcraid (Both from the NVME_DID) Folder contained in the AMD / Chipset Drivers / Raid Drivers
*Order is critical.
Ver: 9.03.00.206 from: https://www.amd.com/en/support/chipsets/amd-socket-strx4/trx40
Notes:
Boot Method: Windows 10 boot USB created on a Win10 machine with MS MediaCreator. Partitioned USB Drive into 2 separate partitions. 1st Windows 10 Boot, 2nd Driver Storage (Loaded above drivers to this partition). Win10 Installer did not see second USB partition until I selected "Rescan" in driver loading section of install.
Big gotcha when the windows installer comes up do not delete any partitions. If you do- it will also delete the critical RAID information on the disk and you will not be able to install the OS. This info is buried in the guide above.
Pay close attention to the RAID setup in the BIOS. When you setup an array it initializes the array and stores the array config on the drives. When installing windows and after you have loaded BOTH the additional drivers (rcbottom then rcraid) you will see the RAID volumes and other volumes. If you do not see the RAID volumes go back to BIOS delete and rebuild the array(s).
Deviated from DOC by not enabling CSM BOOT. When done properly one can conform to the new MS UEFI security and still have RAID.
SATA Drive connections in SLOTS 1 & 2 worked. Had to move the drives to the first two SATA ports on the MB to get RAIDXpert2 config to see the drives even though the MB saw the drives in other slots. Until moved to port 1 & 2 the drives did not become available in the RAID config utility.
My Raid Setup:
2 X M.2 1tb RAID 0
2 X 6tb SATA RAID 0
*Awaiting parts to convert both RAID0 arrays to RAID10.
My Specs:
MB: ASUS Zennith II Extreme Alpha BIOS: 1402
CPU: AMD Ryzen 3960X
Mem: 64GB Corsair 3600 DDR4
M2: Samsung EVO Pro 1tb x2
SATA: WD Red Pro 6tb x2