MapQuest map tiles are no longer displayed.

MapQuest has discontinued direct tile access of its maps, and so when using a Map Source of either MapQuest-OSM or MapQuest Open Aerial, the map tiles will display an error message saying: "As of July 11, 2016, direct tile access has been discontinued".

Currently, the only work around, is to use a different Map Source, such as Mapnik or Bing Aerial Maps.

We are looking to see what it would take to re-introduce MapQuest and/or include some other Map Sources, in a future release.