FWIW, also struck me last week. I posted a question on the Unix StackExchange, since AskUbuntu doesn't allow "Ubuntu +1" questions: "Dual monitor confusion in Ubuntu Gnome 17.10" =
https://unix.stackexchange.com/q/389785/99759
I don't know whether some of the data posted there will help...
FWIW, also struck me last week. I posted a question on the Unix StackExchange, since AskUbuntu doesn't allow "Ubuntu +1" questions: "Dual monitor confusion in Ubuntu Gnome 17.10" =
https:/ /unix.stackexch ange.com/ q/389785/ 99759
I don't know whether some of the data posted there will help...