This was working, but now isn't. The XFCE power manager has the suspend and hibernate options greyed out, and the KDE menu "Leave" page has only "Log Out" and "Lock Screen" displayed.
My first thought was to check that my user is in the power group, but that seems fine. Same groups as usual, and obviously the same groups as before the most recent update.
When I push the suspend button, configured in XFCE power manager to suspend, and which previously suspended, is says "Not Authorised". Using the command
dbus-send --system --print-reply --dest="org.freedesktop.UPower" /org/freedesktop/UPower org.freedesktop.UPower.Suspend
also tells me it's not authorised. I am perplexed.