B550-A Pro M2_1 Slot not working?

There are two types of SSDs: SATA and NVMe SATA uses an older interface with one designed around hard drives while NVMe is designed for flash memory

If you want to use 4 SSDs on one adaptor you need to put it in a slot which gets 16 lanes

cannon cove slot 2 PCIe NVMe SSD will not be compatible with your SATA port Basically, different protocols and interfaces are used in both these connections

can you run pcie 40 in 30 slot 2 specification supports NVM Express as the logical device interface for PCI Express SSDs, in addition to supporting legacy Advanced Host Controller