If you hover over the little red "!" in the system summary table you will see the number of actions reported for this system. If you click on this you will see a pop-up with the details of the actions. Some systems show an action count of 1 when you hover but the pop-up says there are no actions for this system. Also, all of the action counts reported when hovering are either 0 or 1 (so a system with 5 actions will show only 1 when you hover over the red "1").