It seems bizarre, but the who and w utilities say there are no users on my system.
My account is an Active Direcotry account and sssd is running.
johe@ibis:~$ who
johe@ibis:~$ w
10:09:26 up 16:47, 0 users, load average: 0.60, 0.59, 0.48
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
I guess this is known behaviour?