It sounds like this problem may be limited to Wayland sessions (which includes the login screen). Please try this workaround next time you install 18.04:
Ctrl+Alt+F4, log in, edit /etc/gdm3/custom.conf and uncomment the line: #WaylandEnable=false
Then reboot.
It sounds like this problem may be limited to Wayland sessions (which includes the login screen). Please try this workaround next time you install 18.04:
Ctrl+Alt+F4, log in, edit /etc/gdm3/ custom. conf and uncomment the line: false
#WaylandEnable=
Then reboot.