On the NUC BIOS interface, did you?
- Enable Legacy boot, and not UEFI.
- Set your boot order to boot from your SSD or M.2 first.
- Disable network boot.
- Enable USB boot, but make sure your SSD or M.2 has boot priority.
(Instructions copied and edited from a tutorial that a member, @Rugby I believe, posted here not long time ago).
Also, according to another member:
“Something I realized about the new Bios is that you have to make one change at a time and save. Otherwise any other options associated with the change won’t appear.”