Asus WS-C621E-SAGE Memory Issue

[notacake]

I have an Asus WS-C621E-SAGE motherboard with the current test setup:

1x Xeon Bronze 3104
1x Samsung DDR4-ECC 2933 64GB M393A8G40MB2-CVF

Both of these parts are in the AVL for this board.
No other hardware is connected aside from the 750W PSU and fans.
I have both 10 pin CPU connections in place.

Yet it refuses to boot with the error "Abnormal memory" and code B0 (the initial BIOS screen does come on but doesn't progress past this).
If I try with a Kingston KSM26RS8/8HAI 8GB module - also on the AVL - it boots fine. So I know the motherboard and processor are working.

I don't have another DDR4-ECC system to test the Samsung modules on, but I've tried all 6 that I have (one at a time) and they came from a reputable reseller - so I'm not yet convinced they're bad.

So my hope is that there's some BIOS related incompatibility between the CPU and RAM which could be patched.

Is there anyone who could help me with this? I have experience with reverse engineering, x86 assembly, debugging interfaces, etc - but not with BIOSes, so I would really appreciate some guidance in exploring it if no-one has any straightforward answers.

ETA: I have contacted Asus tech support for this, they informed me I'd have to arrange a replacement/refund with the seller of the motherboard - despite the motherboard working just fine.
ETA: My BIOS version is 6201