This is related to events coming from one or more monitors, which the system might treat as a reason to wake up. Sometimes a monitor will add/remove audio support, or disconnect entirely, when going to sleep. And that can give the OS the impression that something important is happening which should wake the machine.
There are plenty of bug reports about these issues but I'm not sure which one this is. ** Package changed: xorg (Ubuntu) => mutter (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/2106437 Title: monitors never dpms off when three present To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2106437/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
