I just had the same problem. if anyone have it, for me the problem is that my app is a Channel app too, so it need an ADDITIVE ICON in the Channel navigation menu extension. it require a SVG icon also if yoi don't have any menu item.
SET it and you will access the listing settings.
The problem is the bad redirect to the main icon page... i wrote to the support about this today. hope it will fix ASAP.