I have had this problem in the past and it reemerged on an upgrade from 16.04 to 18.04 and have resolved it. For me (Lenovo Yoga) the issue is with USB rewaking the machine.
The following fix worked for me. 1) Created file: /etc/systemd/system/toggle.XHC.to.fix.suspend.issue.service with following informaiton [Unit] Description="Make suspend ignore USB wake up." [Service] ExecStart=/bin/bash -c "echo XHC >> /proc/acpi/wakeup" [Install] WantedBy=multi-user.target 2) Created a symbolic link to above script in /etc/systemd/system/multi- user.target.wants 3) Executed following commands sudo systemctl daemon-reload sudo systemctl start toggle.XHC.to.fix.suspend.issue.service 4) checked service was started with sudo systemctl status toggle.XHC.to.fix.suspend.issue.service 5) Enable it on boot with sudo systemctl enable toggle.XHC.to.fix.suspend.issue.service Notes: -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1574120 Title: Notebook doesn't suspend when lid is closed after update to 16.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1574120/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs