Thank you for your attention. I installed the latest armbian (focal, kernel 5.8.6) to upload logs. And nvme ssd was detected!! I tested the other images (kernel 5.7.15 and 5.4.46). All versions worked fine. I can't explain why this happened. I'm just guessing it might be a compatibility problem with nvme ssd. I'm sorry for the confusion to you.
Hello, I have used NanoPi M4v2 with "NVMe SSD adapter" (Officially sold by the FriendlyElec). NVMe SSD is detected when I installed ubuntu based kernel 4.4. (FriendlyCore 18.04 or Armbian Bionic desktop based kernal 4.4.y) But When I installed armbian based kernel 5.x, NVMe SSD is not detected. Anyone can advise?