I am noticing that recently my laptop does not go to sleep/lockout after its configured X minutes of inactivity like it did in the past. I suspect some program (like media player does) is preventing it from going to sleep. I do not have any media player running, so how can I find which program is preventing it from sleeping?
It does go to sleep if I close the lid. But I would also like for it to go to sleep after X minutes of inactivity.
Update: Upgraded to Ubuntu 18.04 with default Gnome and Wayland enabled.