The Gillion's Iris Web Portal has a tool that allows you to download your Z-wave mesh map, which looks kind of like an old Spirograph drawing. It shows in graphic form what path your devices use to get a signal to the hub, i.e, what other Z-wave devices are in the mesh between your problem device(s) and the hub. You may find that just one device is causing all your trouble if it is in the mesh path for the problem switches. I believe at least some customer service folks have access to analytics that show that information as well (not sure if Tier 1 uses it).
The tool is accessed through the little red wrench at the bottom of the menu on the left, just above the Donate button. There is also a download button for Graphviz that allows you to read the map. There are posts from several months ago that give some detail on how it works.