ArcGIS Storymaps Collection has a bug where it does not load base maps. I have attempted to load several base maps and the issue persists.
Link to County dashboard
Link to Cities, towns and places dashboard
For some reason, the topographic base map I am using for both dashboards does not load, but the shaded relief does. The dashboards base map successfully loads outside of StoryMaps.
On a related note, it is annoying that ESRI did not continue the tabbed navigation capability in the new Storymaps. I have had to re-create my content in Storymaps Classic, which is unfortunate.