I had the same issue. When computer goes to lock screen the dock is visible and when i enter password to log in top bar crashes. Also i can't control other open windows or access dock. It stopped when i removed "Top Panel Workspace Scroll" and "Workspace Indicator" extensions. Hope this information helps.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1769383 Title: Ubuntu dock/launcher is shown on the lock screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1769383/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs