PCIe Storage Expansion Card not detected in BIOS

Hi there,

I have a b550m itx/ac and I wanted to get some more SATA ports on it for more storage since its going into my NAS system. I got a StarTech 2-Port PCI Express to SATA Expansion Card which said plug and play yet when I plug it in, it doesn't seem to work. Confused, I tested with another PC I have and it does work. I'm running a 4600G as my CPU.

Is there a BIOS setting or something that I need to enable to get it to function? I've seen forums saying this but there were for different vendor boards.

I also built a NAS system using the b550m itx/ac motherboard, mainly because it was one of the few options for ITX available. NAS is a 5 bay but the motherboard only has 4 SATA ports so I added a PCIe expansion card with two extra SATA ports. Previous tried replacing the WIFI card with and M.2 A+E two port SATA card. When that didn't work I bought another thinking the first may be bad. When the second didn't work I bought a PCIe card with two SATA ports. Problem is the 5th drive isn't being recognized in BIOS. When I boot to Unraid the same, I see four of the five drives. Is it the motherboard that is the issue? I have replaced cards, cables and drives. I know all the parts are good.