I'm running Xubuntu 18.0.03, which hasn't reached end-of-life, and this bug is still present. It was introduced when I upgraded to kernel 5.0 with xorg 1.20.4-1ubuntu3~18.04.1. It can be circumvented using either of 2 methods:
1. Uninstalling light-locker and installing xscreensaver or 2. As suggested by @bbethge, created /etc/X11/xorg.conf.d/20-intel.conf: Section "Device" Identifier "Intel Graphics" Driver "intel" EndSection -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1801609 Title: Fails to deactivate dpms off mode after user initiated wake-up events(not system-suspended, just locked and dpms active) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1801609/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp