Asus Rog GL12CP: SSD M2 NVMe compatible ? ASUS say YES but...

[MGCoteau]

Hello. I have an Asus Rog GL12CP PC. Bought in win10 I have since reinstalled it in win11 (24H2). The system is installed on an M2 SSD in SATA, and the data is on an HDD. I would like to change the SATA SSD to PCIe to gain speed. ASUS confirms that the M2 port is compatible with SATA and PCIe. However, my new M2 NVMe SSD is not recognized (WD_Black SN770). I changed SSD, same problem.
How can I know if it is a compatibility problem, a setting problem or missing drivers? Thank you for your suggestions.

[achugh]

What is the capacity of this NVMe drive? Is it more than 1 TB or more? Also WD_Black SN770 is a PCI GEN 4 Drive and I believe your PCIe slot is GEN 3. Now GEN 4 drive should be backwards compatible to GEN 3 but it seems you are having issues. Do you have the latest BIOS installed for your PC?