Commit 147a743d8d moved the suspend and power-off actions into
the submenu that contains the log-out and switch-user actions,
but did not update the submenu visibility logic to account for
the additional actions.
As a result, the submenu is hidden when log-out and switch-user
are unavailable (like on the login screen), even if suspend and
power-off are enabled.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/2169