Upon exiting the desktop by choosing shutdown or reboot you end up at login directly without computer shutting down.
Also suspend failed for me.
(Probably also not hibernate but i can not tell due to bug 3375 )
Workaround: change to GDM (MCC->Start->Session_manager (i guess is english version) ( ref: bug 4605 )
That alone solved my shutdown, reboot, and suspend problems.
Sidenote: Another but separate issue 4475 is making shutdown pause a minute with black screen before last steps shutting down.
EDIT: 4475 fixed today by systemd 43
/EDIT