Setting the extent for a custom basemap in the ArcGIS Open Data site configuration shows the extent at a different zoom level when viewed in the live site, if the custom basemap uses a projection other than Web Mercator Auxiliary Sphere (102100).
Last Published: October 19, 2015ArcGIS Online
Bug ID Number
October 16, 2015
June 11, 2020
After review by the development team, it has been determined that this issue is related to a known limitation with the software that lies outside of Esri's control. The issue's Additional Information section may contain further explanation.
If basemaps are not created in enough different zoom levels, it is not possible to get the optimal user experience.
Use a custom basemap in the Web Mercator Auxiliary Sphere (102100) projection.