Suspend, restart and power off don't work, crashes the system and logs me out.

Thank you for your bug report. Could you try to restart, log back in and then do 'journalctl -b 0 > log' and add the log to the report?

Thank you for responding. I tried to restart, but all I got was a flashing cursor in the top left of my screen. So, in the end, I had to reinstall Ubuntu from scratch. The same problem re-occurred again, and forced me to re-install from scratch a third time. This last time, from the very first boot after removing the installation media, I went to the Nvidia app and switched from "On-demand" to "Intel only". This time it rebooted in Wayland, while giving me also the option to boot into X.org or Classic Gnome, and everything worked perfectly, both in Wayland and in X.org. Finally, just to try once more to use my Nvidia card, prepared as I was to re-install fresh one last time, I set Nvidia to "On-demand" and booted into X.org (Wayland wasn't offered) without any problem persisting at all. Therefore, I think the problem is something to do with the Nvidia card not saving the relevant setting in on first boot into "On-demand" mode, and you need to set it to another mode and then switch for the settings to be saved correctly. Otherwise, I can't explain it. I did nothing strange with any other settings, installs or configurations. I believe, therefore, that it is the Nvidia card, with the Nvidia proprietary driver, that is preventing the computer from suspending, sleep, hibernating, starting, powering off (by command or GUI - only button physical button works), or whatever. It seems that the Nvidia card stays active, preventing the system from deactivating. Apart from that it could possibly have something to do with the HDPI screen, that requires fractional scaling to be usable, although I hadn't yet set fractional scaling when I had the problems. Of course I can add the log if you think it would help, but right now I have a perfectly functioning system (apart from the apt get installed Firefox which glitches in the menu and consumes excessive RAM - most likely unrelated - and is resolved by uninstalling the apt install and installing the Firefox Snap). Thanks!

[Expired for gnome-power-manager (Ubuntu) because there has been no activity for 60 days.]