I've been having issues on my 2x2 cluster with the map working under various circumstances.  We went through a series of progressions of things working and not working, and it looks like we have an overall fix for map issues on our private server.  Maps are now working in all instances including the main map, zoomed in maps, treasure maps, and maps on clustered servers.  One caveat is we are using Nitrado hosted servers, so YMMV depending on your setup.  Thanks to a few different threads on this