I'm using Cinnamon on Mint 19, although my problem started earlier, on 18.3 (which is why I upgraded to 19 in the first place).
I used to have my screens (I'm on a two monitor system) to turn off and eventually the computer to suspend using Power Management. Since a few weeks, just after the screens turn off at the scheduled inactive time, within 3-5 seconds they turn on again, with all content from the secondary monitor moved to the primary screen. Obviously, the computer will not suspend either.
After upgrading to Mint 19 the problem is still there. On top of that, probably for the same reason, TLP does not turn off the screens nor lets it the computer go to sleep.
What I've done so far:
- Made sure wakeup for all devices is disabled;
- Closed all programs;
- Checked with system monitor that no process is using CPU;
- Wondered what else to do.
Any ideas? What can I check next?