I am not from Intel but much of what you describe sounds like problems that occurred in a couple Intel driver versions between 4080 and 4206. Upon wake up the screen would have problems such as flickering and/or not representing reality (which can be confusing - like you said you might see desktop/icons but can't click); workarounds were to unplug/re-plug the HDMI cable or power-cycle. Some people prefer to run old 4080 driver but many presumably run current 4222 driver. I'm not saying that 4222 is perfect - I still sometimes get flickering around the bottom 9% of my 1920x1200 monitor - but if you are seeing worse symptoms then your actual driver may be some version between 4080 and 4206. A thread where Intel says they are looking into things is NUC NUC5i5RYH HDMI Sleep Issue
I've had mine for about a week now and had same problem once so far.
Only the desktop wallpaper is visible on the screen after wake up and all the icons on desktop, taskbar etc are gone so basically you can't do anything.
Pressed ctrl+alt+del to get task manager so I can restart but it wouldn't show up, changed the desktop screen resolution but same problem. So I had to restart manually by pressing the power button on the NUC.
Heaps of people with NUC5i5RYK + HDMI are having similar problem and its caused by Intel video card driver I think.
NUC Model: NUC5i5RYH (0249 BIOS)
O/S: Windows 7 64bit
GPU Driver: 4222
Cable: Mini Displayport to Displayport
LED: 28" Samsung U28D590D
Use 4080 driver cos that should fix the sleep recovery problem. Link Intel® Download Center
I'm gonna also use 4080 if it happens again.