M.2 drive not showing in windows

New PC build … using Gigabyte X670E Aorus Master

I have a Corsair 2 TB M.2 PCIe-5 module in the primary M.2 slot (slot 1) and working fine.

I have a 2nd 4 TB M.2 module (WD_Black) that is PCIe-4 that I wish to use in slot 2 (PCIe-5 slot)
It does not show in W11 Device Manager or in Disk Management.

If I move it to slot 3 (PCIe-4) and it comes up in W11 fine.  (same if in Slot 4)

As PCIe-5 is supposed to be fully backwards compliant, what do I need to do to get this to work ?
I have tried various support forums the only suggestion is that this is a BIOS issue, no BIOS settings have been changed.

Want to use slot 2 as it has direct access to CPU not the storage controller, so maximum speed, and signalling.

PCIe versions are backward compatible.  According to Gigabytes website it doesn't suggest that the M2B slot shares bandwidth with anything else but it's functions are dependant on what CPU is installed.

Personally I think I would try to isolate the problem.  You could test whether it's detected by BIOS if you remove the SSD from M2A.  You could also test whether it detects if you move the Corsair drive into the B slot.  If that fails, to see whether the GPU is a factor you could test if the slot is functional when using integrated graphics.  If all fails, it might be a case of the slot being non-functional with any combination of hardware and therefore I'd consider returning the motherboard.

In slot 2 nothing visible .... move to 3 or 4 and it shows, 

Exchanged the motherboard .... still the same.

So basic testing has been done.

I am not familiar with playing about in BIOS, but can look u anything specific.

I looked in BIOS it lists only the M.2 in slot 1 (a)

Nothing for slot 2 (

I’ll swap the 2 modules over tomorrow, and see what that shows.