When the external monitor is connected, the notebook can't go to sleep!

When the external monitor is connected, the notebook can’t go to sleep!

My System Info

My Power Settings

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