systemd session not terminated after login

[William]

I've recently migrated to systemd, with the following versions of relevant packages (under Gentoo):

lightdm 1.10.1
lightdm-gtk-greeter 1.6.1
systemd 212-r5
xorg-server 1.15.0
xfce4-session 4.11.0-r1

I use lightdm as my display manager, and XFCE as my desktop environment. Since migrating to systemd, I have not been able to shutdown/reboot my computer from within my XFCE session. The commands are not available as systemd sees two logged in users. The first is root, and the second is my user. The root session is started by lightdm-greeter, but seems to never get terminated. As a result, I cannot shutdown from within XFCE (although once I log out of XFCE and am at the login screen, I can shut down just fine).

The only customisation of the gtk greeter that I've done is changing the background. Is there something else I've missed?

$ loginctl
   SESSION UID USER SEAT
        c1 0 root seat0
        c2 1000 enigma seat0

2 sessions listed.

$ loginctl show-session c1
Id=c1
Name=root
Timestamp=Sun 2014-06-15 08:54:19 EST
TimestampMonotonic=4230126
VTNr=7
Display=:0
Remote=no
Service=lightdm-greeter
Scope=session-c1.scope
Leader=236
Audit=0
Type=x11
Class=greeter
Active=no
State=closing
IdleHint=no
IdleSinceHint=0
IdleSinceHintMonotonic=0