lightdm can't login to desktop session with gnome-flashback at Ubuntu18.04

[chenyu]

Environment:
Ubuntu18.04 (fresh install)
lightdm
gnome-flashback
domain user with PBIS joined domain

root@ubuntu1804-2:/var/log/lightdm# lsb_release -rd
Description: Ubuntu 18.04 LTS
Release: 18.04

root@ubuntu1804-2:/var/log/lightdm# dpkg -s lightdm
Package: lightdm
Version: 1.26.0-0ubuntu1

root@ubuntu1804-2:/var/log# dpkg -s gnome-flashback
Package: gnome-flashback
Version: 3.28.0-1ubuntu1

Problem:
local user can login to gnome-flashback desktop fine, but for domain user, after enter password at greeter, lightdm is restarted and return back to greeter, no desktop session can be created.

But for the domain user, login works fine at Ubuntu(default), Mate and KDE desktop environment.

Log: (please see full log in attachement)
.xsession-errors: Failed to set environment: Process org.freedesktop.systemd1 exited with status 1
lightdm.log: [+4471.62s] DEBUG: Session pid=8524: Exited with return value 1

Any help is appreciated.