When the external monitor is connected, the notebook can’t go to sleep!
My System Info
I recorded 2 videos:
when monitor connected
when - disconnected
Monitor connected via HDMI.
I tried with 2 different monitors - the same thing happens!
Under Windows 10 - works fine!
Does it work if you press the sleep button from the menu or using systemctl suspend ?
Please post the output of systemd-inhibit --list