The LayerList widget in 3.15 has some additional functionality, including showing the legend. However, the legend doesn't get updated when the checkbox on a layer is clicked. It will only update when the map is zoomed in or out. It will not update if the map is panned.
Ken,
I am seeing the same thing. Are you going to call this into Tech Support?
Yes, I have called it in. Currently, their work-around is to use the toggle event to refresh the widget when a layer is toggled. Unfortunately, this has the side effect of collapsing the LayerList widget every time you toggle a layer.
myWidget.on("toggle", function (){ myWidget.refresh(); });
This doesn't have any effect on the startup issue, though. I tried refreshing the widget when the load event is fired, but that leaves the legend totally empty.
This has been fixed in 3.16
ENH-000092811: Layerlist widget now updates the legend on the toggle of the sub layers.