I run a permanently working macro with a "repeat actions" loop.
For not overstraining my screen, i put 3 actions in a row at the end of the loop: "Sleep screen" "pause: 15 min" "Wake screen".
But after the 15 min, the screen stays dark.
When i change the pause to 1 min, "wake screen" works and the loop restarts.
So I guess it has something to do with the settings of my computer, but don't know which.
The same arrangement with "Start screen saver", pause, "Stop screen saver" doesn't work at all.
I can't tell from your explanation if (after 15 minutes) just the display is asleep, or if your Mac is asleep. If the latter, KM can't wake up anything. When the Mac is asleep, the KM Engine can't run.
I guess too that the mac is asleep and some settings send them asleep sometime after 1 minute (because with pause = 1 min the action "Wake screen" works).
But I have'nt found settings that determine that after a certain amount of time the mac shold go asleep (I just found Settings - battery - time schedule a posibility to fix times, when the mac should go asleep)