I've had numerous dual monitor issues with my NUC5i5RYK which always seem to be different depending on which OS and/or drivers I'm running. I'm now using Windows 10 64 bit with the the 10.18.15.4256 driver. When the computer wakes up from sleeping (I'm using intel ready mode which has quiet hours) both monitors don't always wake up. Only one does. The fix is to turn the "on" monitor off and then back on and then they both wake up. Intel are you aware of this issue? I didn't have it with some versions of the drivers in windows 8.1.