I understood; you are turning on and off the NUC disconnecting the power source. NUC is an electronic device as well as the power adapter and they have internal chips to protect from power source failures. NUC is protecting itself from damage.
Also the operating system might get corrupt if it is not possible to turn it off using the shutdown option.
Please let me know if I am misunderstanding you.
The application for this unit is in a digital display signage, which is mounted inside the display.
so the power for the area is controlled remotely, and the device needs to boot up each time the power is restored.
The Linux UBUNTU OS is used because it is stable in this situations, we use this in other application with other standard mother boards.
this is the first time we have used the NUC, and was hoping to swap over the designs to incorporate the NUC into all our new signage.
It seems the BIOS is not hand-shaking with your operating system properly after long power failures; It is necessary to restart the system.
Please do this troubleshooting, get into the BIOS, Power tab and change the After Power failure option to Last State instead of Power On. This troubleshooting worked on Windows® 10.
Let me know the behavior.