EsriControlCommands appears to stop working if MapControl is docked to all four sides of a form and the form is minimized/maximized while tool is active.
workaround = Do not dock to all four sides.It appears that slightly adjusting the size of the mapcontrol links the command back with the map. If you are working with the zoomin and it stops working, slightly adjust the size of the form and the map will then show the zoom.