After I close the lid of the laptop it doesn't enter in suspend mode. This happened immediately after an update of Ubuntu 18.04. I use the setting suspends when the laptop lid is closed OFF until I find a solution.
Why it doesn't suspend mode work?
In Ubuntu 18.04 Gnome desktop, there’s no option in Settings utility for configuring laptop lid close actions. And Gnome Tweaks only offer a switch to enable/disable ‘Suspend when the laptop lid is closed.
Follow the steps:
sudo gedit /etc/systemd/logind.conf
Save and exit the file.
systemctl restart systemd-logind.service
That's it, This method will fix your issue.