The issue seems created by the gnome-session changes from 3.24.1-0ubuntu5
" * Backport patches from 3.25.3 to kill D-Bus clients on log out.
This works around GNOME Online Accounts not working correctly
after logging out (LP: #1610944)"
It fails every time to login it again here but downgrading gnome-session to the previous version fixes the issue.
Note that the problem is not specific to lightdm, the behaviour is the same using "startx -- :1" to start the session
The issue seems created by the gnome-session changes from 3.24.1-0ubuntu5
" * Backport patches from 3.25.3 to kill D-Bus clients on log out.
This works around GNOME Online Accounts not working correctly
after logging out (LP: #1610944)"
It fails every time to login it again here but downgrading gnome-session to the previous version fixes the issue.
Note that the problem is not specific to lightdm, the behaviour is the same using "startx -- :1" to start the session