Hello Simon, I am sorry to hear that you are having this kind of problems on your NUCs.
I tried to install a BIOS image on another NUC with UEFI disable. The BIOS image had UEFI enable, so once the updated was done I check the BIOS on the NUC and it had UEFI enable.
I did not experience any boot problem when trying to go to Windows.
Would you please let me know which software or utility did you use to create the BIOS profile?
Could you please send me a picture where it shows the Windows bootloader (partition 0)?
Thanks for taking time to address this issue. To reproduce this problem just setup two nucs identically in uefi mode (uefi and legacy mode enabled together). In my case i created a windows 7 enterprise x64 image for deployment. So i have to identically installed nucs
Once you are set up, enter bios on one nuc and click on the User-Icon in the menu bar. there you can save your settings to a profile, export that to a usb device and import that on the other nuc. Reboot and when you reenter the bios there should be at least two Windows bootloader (partition 0) entries under uefi boot section. You can reimport the bios profile and it should add more of these entries ;-)...
To solve the problem i also tried to remove bios battery overnight and see if the bootentries have been removed, no luck...
Anyway this afternoon i found the solution for me. I recreated the bootpartition and bcd store on the for the 3 affected nucs and the strange entries were gone.
Since i am not a specialist on uefi firmware, i don't know where exactly the problem was, but i assume it had to do with partition guid that was dublicated in the boot entries or something like that. It would be great if one of the engineers could provide a technical answer to that.
In my opinion the profile importer should not allow foreign bios profiles if this is not supported. Thanks for fixing this, for future bios releases.