I had Windows 10 installed on a 1TB Crucial NVME M.2 SSD with 32gb of RAM.  It worked fine until one day, the unit would not detect the M.2 SSD.  Tried a different M.2 in the port, same result.  Tried my Crucial SM.2 SD in an enclosure on another PC and it was detected.  BIOS was reset with the latest version using the jumper/F9 method; nothing. Obviously, the NUC's motherboard is at fault and Intel won't RMA it because the serial # shows a secondary market distributor.  $1,200 in the trash and no wonder Intel's stock has never done anything.  Inferior product development and customer service won't foster customer loyalty.  A search on my issue shows it is common on these units as they age just a few months.  Steer clear.