We're noticing that services at shutdown don't always run. It's most evident with systemd-update-utmp-shutdown.service which should be logging to lastlog, but definitely isn't:
$ last | grep 'system boot' | sed q
reboot system boot 3.7.3-rampage Thu Jan 24 13:57 - 17:47 (9+03:49)
I have VMs which I've built recently which have no reboot entries in lastlog.
This is reproducible with the latest git commit as of this filing (cdf173349c73c9)
Downstream bug report: https://bugs.archlinux.org/task/34708
So this is caused by systemd-update-utmp-shutdown.service pulling in start jobs that conflict with stop jobs for the same unit that are created by shutdown.target.
I fixed this now in git: