If the maps in Kibana dashboard are not loaded in Skedler reports, it is because Skedler server might not have an Internet connection. Kibana loads the map tiles from mapquest which requires network connectivity. So the system where you use the browser to view Kibana needs an Internet connection. Similarly, Skedler opens the Kibana URL inside the server itself so, to load the map tile from mapquest Skedler server requires network connectivity.
To resolve this issue provide Internet connectivity to Skedler server.