https://github.com/linuxmint/mdm/issues/148
Fast relogging in breaks work of pulseaudio, it stops detecting new devices
I have noticed that waiting for 20 second in mdm (or lightdm whatever) solves this problem. AFAIC this happens because xfce4-session doesn't have time to kill all user processes in time and gives control to mdm (or any DM) too early