Launching Users panel as non-admin shows polkit auth dialogue
Launching the Users panel from a non-admin account will show a gnome-shell polkit authentication dialogue as the dialogue is opened. It's likely that the panel is trying to access information that a non-admin would not normally have access to, and triggers a dialogue. No dialogue should be shown until the "unlock" button is pressed.
There were 2 accounts on top of the "root" account, one non-admin user which gnome-control-center was running as, and another admin user.