Go into setup - is the disc set up in Intel RAID (IRST) mode?  If so, you either need to turn IRST off, or load the OS install driver for IRST before Windows will see the drive. [URL]
Having some issues doing a disk clean on a Dell Latitude 7320. Not sure if there are some settings in the bios i need to change. I am booting into a win10 usb and selecting repair, going into command prompt and using diskpart. When I use diskpart and use the list disk prompt the only disk I am able to see if the USB and not the onboard SSD drive.  Thanks, Ricky
Unable to see disk in diskpart