MAXIO MAP 1602 - no driver?

Good morning, been trying to get two different PCIe to nvme adapters working in a Lenovo P520:

Intel C422 chipset - updated BIOS
Xeon w-2135
16gb
PCI Radeon 9200 64mb
RIItop 4x nvme PCIe or ASUS Hyper M.2 V4
4x Teamgroup 2TB nvme
TrueNAS SCALE 25.04, new install

The only devices installed are two onboard m.2 nvme slots, the dvd drive, PCI svga (non-e) video, and one m.2 riser board.

I have tried both PCIe slots 2 and 4, with and without bifurcation. Without, I only see 1 nvme, as expected. With x4x4x4x4, I see only two. I have tried manually setting PCIe options, as well as automatic. I have disabled all unused devices in the BIOS.

lspci -v shows:

b4:00.0 Non-Volatile memory controller: MAXIO Technology (Hangzhou) Ltd. NVMe SSD Controller MAP1602 (DRAM-less) (rev 01) (prog-if 02 [NVM Express])
Subsystem: MAXIO Technology (Hangzhou) Ltd. NVMe SSD Controller MAP1602 (DRAM-less)
Flags: fast devsel, IRQ 48, NUMA node 0, IOMMU group 5
Memory at fbd00000 (64-bit, non-prefetchable) [size=16K]
Capabilities:
Kernel modules: nvme

b5:00.0 Non-Volatile memory controller: Phison Electronics Corporation PS5027-E27T PCIe4 NVMe Controller (DRAM-less) (rev 01) (prog-if 02 [NVM Express])
Subsystem: Phison Electronics Corporation PS5027-E27T PCIe4 NVMe Controller (DRAM-less)
Flags: bus master, fast devsel, latency 0, IRQ 52, NUMA node 0, IOMMU group 6
Memory at fbc00000 (64-bit, non-prefetchable) [size=16K]
Capabilities:
Kernel driver in use: nvme
Kernel modules: nvme

Devices b3 - b6 exist, but I only included one of each for brevity.

The above is for a RIITOP Quad nvme. I get the same behavior from an ASUS Hyper m.2 v4.

It appears that the Kernel driver for MAXIO is not loading, but for the Phison is?

What am I doing wrong - or, am I using known inop nvme riser cards?

Thank you

EDIT: It also takes 5+ minutes to boot.

I don’t have an answer to what your issues stem from, but there were a lot of reports of issues with the MAP1602 in Linux land 1.5 years ago. Perhaps there are some residual bugs still.