This issue caused lots of problems for me, as I only had a USB 3.0 stick handy, and I simply could not install the operating system on the NUC using that stick.
I had no choice but to buy a USB 2.0 stick and use that to boot off to install the operating system on the NUC.
Now the operating system is installed, attaching a USB 3.0 drive/stick works okay and it functions perfectly. However, I must make sure I remove all USB 3.0 devices when rebooting or powering on the NUC otherwise it will hang. Then I can re-attach them after the NUC has booted up. A big hassle of course. I hope Intel fixes this.