I have a 2017 27" iMac running macOS 10.13.6.
I have configured the sleep / auto lock settings as per the below screenshot. But for some reason the computer wont sleep / auto lock.
I have an application downloaded from the App Store called Owly installed, which is similar to Caffeine, but this is currently disabled and not set to keep the screen on.
Ive noticed that it will sleep if i log out of the user account and leave the machine on the "chose user" login page. But not if the user is logged in.
Any ideas?