It took me some time to understand how to turn back to Xorg; you didn't say it. Upon uncommenting the line
WaylandEnable=false in /etc/gdm3/daemon.conf and rebooting, I failed to reproduce the defect as of today. $ aptitude show texlive-binaries| grep Version Version: 2018.20181218.49446-1 $ aptitude show xorg| grep Version Version: 1:7.7+19 As far as I'm concerned, feel free to close the bug report.
