I have layers within a group in a service that uncheck automatically when you either zoom in or zoom out. So if you are zoomed out on the map and turn on the layer group it displays, but if you zoom in the sub layers uncheck. With the same layer group if you are zoomed in and turn on the layer group it displays, but if you zoom out the sub layers uncheck.
I have this layer group set to show layer at all scales. There are other layer groups in this same service that show up ok at all zoom levels and do not automatically uncheck.