CommentStreams:169b4967bf718cb4c142b94f4912fadf

Sorry for the late reply.

The main problem is compatibility. Your Crucial P310 is a PCIe Gen4 SSD with a Phison controller that cannot work at lower speeds, so the Raspberry Pi 5's native PCIe port cannot detect it.

The X100x is just a PCIe adapter, which only changes the port shape and does not affect compatibility at all. The real issue is that this SSD does not work with the Raspberry Pi 5 itself.

We recommend using another SSD that fully supports the Raspberry Pi 5’s native PCIe interface.

For more reference and discussions:

Raspberry Pi5-bootloader doesn't detect nvme, Crucial P310 PCIe Gen4 M.2 - Compatible?, Details of Raspberry Pi Compute Module 5 - 2.3. PCIe Gen 2 (shares identical PCIe compatibility rules with the Pi 5)