The login prompt window vanishes if I switch/select/change user in the login window in Ubuntu MATE

[Pavlushka]

The login prompt window vanishes if I switch/select/change user in the login window. And even if I try to switch to a different user being loged in, it leads me to the login wallpaper without the login window. I managed to login somehow by blindly typing my password and hitting "Enter" but its a chance, not a certainty. Like to add, I use an external monitor and disabled the laptop panel as that is malfunctioning.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: lightdm-gtk-greeter 2.0.1-2ubuntu4
ProcVersionSignature: Ubuntu 4.4.0-22.39-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: MATE
Date: Sun May 8 08:43:18 2016
InstallationDate: Installed on 2016-04-29 (8 days ago)
InstallationMedia: Ubuntu-MATE 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
SourcePackage: lightdm-gtk-greeter
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.lightdm.lightdm-gtk-greeter.conf:
 [greeter]
 allow-debugging = true
mtime.conffile..etc.lightdm.lightdm-gtk-greeter.conf: 2016-04-30T11:04:41.593699

[Sean Davis (bluesabre)]

Is this still an issue in a supported release?

[Launchpad Janitor (janitor)]

[Expired for lightdm-gtk-greeter (Ubuntu) because there has been no activity for 60 days.]