Some of the keyboards and mouse devices that have been officially validated can be found here; Tested Peripherals for Intel® NUC Kits NUC5CPYH/NUC5PPYH.
Regarding the issue you are reporting I would like to know if have tested any Windows version, and I would also like to know what is your BIOS version.
Before you are buying a new keyboard try the following:
1. Connect Logitech Unifying Receiver on USB extender cable in order to move it a way from NUC USB3 port (this will reduce the RF interference)
2. Download Logitech Unifying Software: Unifying Software - Logitech Support . Install an run this software. Depress Advanced button and update keyboard firmware to the latest version.
Hope this will help
I was thinking it might be a BIOS issue. At the bottom right corner it says "Visual BIOS 2.2.20" So I don't know if that is the latest version or not. Does 2.2.20 sound right? Or should I try upgrading? I also have the Linux setting checked in the BIOS. Testing Windows is the next thing on my list. I also have the Intel Ubuntu 16.10 video drivers installed as well. But I know Intel doesn't officially support Linux, so it may ultimately just be an issue that comes down to that.
Thanks for the reply Leon. Unfortunately Logitech didn't make a Linux version for those drivers D: But I appreciate the input anyways!
Still you can connect you keyboard to the PC running on Windows and then check the version or update the firmware. Did you try to connect your Unifying Receiver on an USB extension cable instead directly to the USB3 port?