After update to 18.04 from 17.10 my second monitor seems to be detected (though weirdly as " Samsung Electric Company 19" " when it actually is Samsung SyncMaster 940N) but is black. It is set to join displays and I can blindly manipulate stuff on the second display desktop space.
I have vanilla gnome installed though switching to ubuntu styled gnome changes nothing. Forcing no wayland also doesn't seem to do anything.
What can be the problem?