On occasion, when my system goes to sleep, the iMac will not light up the display. The reason i say this is that I have a second 27" 4K monitor attached and I can sometimes log in and that display is working while the built in display does not wake up. If I then choose to restart, they both become active again. On many occasions, neither display comes to life and I have to hard reset the system.
Are you by chance running VMWare Fusion? I have the same problem and last night for the first time I quit Fusion before leaving the office. When I came in this morning my screen woke up as it should. Need to test more but I think that may be the issue.
I am as a matter of fact, but it is usually not running.
Are you using an Apple Watch for 2 form authentication to unlock? I turned that off on my iMac and it hasn't done this in more than a day now. My Macbook Pro is still having these symtoms with this turned on, so now I will turn it off on there as well to see if that resolves the issue at least for now.
Well that wasn't it... after two days I got to it this morning with the screen once again blacked out with no recovery. Hard reset.
Still broken in beta 4 BTW
