Are you connected over HDMI? Can you test it with DisplayPort? Does it happen there as well?
Thank you for joining the Intel communities.
Do you have the latest BIOS installed in your system?
You can download the latest BIOS version here:
Also, I strongly recommend having Windows up to date and all of the drivers; you can download the latest drivers for your system at the following link:
I’m not sure what operating system you have installed on this NUC but you can download the latest Intel® HD Graphics Driver for Windows 10 here: