I'll be able to tell you soon. I just updated my 2012 mac mini to the latest public beta in the hope that the issues will be fixed. I use a Samsung SyncMaster SA850T display, which did not have ANY problems with waking up with MacOS versions prior to 10.12. I even filed a bug about it with apple and provided log files, but they could not reproduce it and closed it. Let's see.I am curious if any of you that have had issues in 10.1X with displayport displays not coming back on after sleep (does not happen all the time) have this issue in 10.13 ?
I just got a Mid 2009? Mini with HS installed. Keyboard strokes does not wake the Dell U2412M display though it wakes the Mini itself with a generic mDP2DP cable. Done the PRAM reset... Unplugged the power cord... Just tried your trick...Get a VESA-compliant mDP>DP cable from Belkin/Accell/StarTech if you're not using one (subtle hint: most cables aren't compliant).
Dells don't ship with compliant cables, swapping out the COXOC junk that shipped with the Dells with a compliant cable "fixed" my issues with my 30-odd Dells in my offices - we now use only Accell cables in my offices on displays that don't ship with compliant cables. NEC and Eizo - which are also in my offices - ship with VESA-compliant cables.
When/if you do get a compliant cable, be sure to reset the display - it will be seen by the PC/Mac as a different device and a new set of Displays overrides will be created for the new cable/display combo.