Oh the double person icon is on the bottom _right_ of the screen if you have more than one user account. I still can't reproduce any old screen contents though.
It sounds like you're experiencing temporary screen burn-in, and in fact the Wikipedia page for that even shows the GNOME login screen! https://en.wikipedia.org/wiki/Image_persistence So I think the grey background is just a pathological situation for image persistence. Not a software bug. ** Changed in: gnome-shell (Ubuntu) Status: Incomplete => Invalid -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/2073637 Title: Screen locking issue To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/2073637/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs