Not really a solution, but there were some issues in the past where RC would fail when the monitor was 'off'.

Seems in some cases, the monitor itself gets removed from the OS as being installed when off....

Maybe run this command to turn off the monitor while logged in...

https://superuser.com/questions/1397941/how-to-turn-off-screen-with-powershell

Then try to remote control to see if you can isolate..My guess if locked devices have gone into some type of sleep state.

I've heard of the issue less, but not sure if that is because people stopped reporting or if it was fixed.....

Presumably our code might be able to wake  up the monitor...but not sure if that is as easy....the reverse code may not always work..I don't recall.

Hi Craig.

From the symptoms I see, that sounds like a distinct possibility. That would explain why it doesn't always happen, and why it works on the 2nd attempt (because of course me moving the mouse around must have woken up the screen). In that case, it seems the RC code can't really deal with the monitor coming on while the RC session is already running. 

I'll try to dupe it with someone being in front of the machine tellng me what he sees.

And just make sure you are not using the "Legacy Viewer" in the ZCC.  I doubt you are but figured I would point that out.  Even if my guess is correct...It very well could be a code "bug" on our part, were we need to detect the scenario and try to wake the monitor or something or it could be a VNC bug....or....