The only recent changes to Ubuntu 18.04 I can see that might be relevant are:
gnome-shell - 7 January 2019 linux (kernel) - A couple of times this month There have been no changes to Xorg or mutter anyway... ** Package changed: xorg (Ubuntu) => linux (Ubuntu) ** Also affects: gnome-shell (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1813896 Title: Monitors stopped working To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1813896/+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