So when lid is closed, OS doesnt suspend or takes long to suspend? The best way is to use journalctl. Close the lid, wait 2 - 5 mins, then open it up and check most recent journalctl messages. Hopefully that gives you some clues.

Now, are you dual booting Windows? Try to check Bios if your laptop has any funny settings for power. On Lenovo, there used to be something like "Power scheme for both Linux and Window" button..

Lastly, xfce4-power-manager app really is just a GUI for your core systemd services. So... as a test, can you not autostart it? Xfce has a setting for that. Or just remove it, you can easily install it back later.
Once youre done, reboot back and check:

1. Does closing the lid make the laptop to go into suspend mode? If yes, great. Test again to see if behavior is erratic, i.e. sometimes it takes 5 sec to suspend, sometimes it does not suspend at all..etc.

2. If above fail, try to run "systemctl suspend" to check if suspend really works on your system.

3. if 1) and 2) fail, you can play around with /etc/systemd/sleep.conf script. Maybe uncomment "AllowSuspend" or something similar....

upower -d can provide some useful info on-demand. I think there’s a daemon component to it too, which may have variable log levels.