I don't have time to try and tackle this, sadly, but I did notice
something potentially useful:
Part of your problem could actually be a bug in update-manager.
update-manager tries to use the org.gnome.PowerManager interface to inhibit
sleep before it tries the freedesktop standard
(org.freedesk
I had this same problem but I fixed it by changing this key in the
configuration editor from "hibernate" to "suspend"
/apps/gnome-power-manager/actions/sleep_type_battery
--
gnome-power-manager hibernates instead of suspending on idle
https://bugs.launchpad.net/bugs/576698
You received this bug
