Craig - technically the basemaps come from ArcGIS Online or ArcGIS Enterprise. Depends how you are signing into ArcGIS Pro. If you go to the Map Viewer, all web maps start with a required basemap in WGS 1984 Web Mercator. Same for inserting a new map view in ArcGIS Pro, it adds a default basemap of your organization. If you do not have a basemap when you share a web map from ArcGIS Pro, it throws a 00216: Map does not contain a basemap error message. Not exactly a "why" answer more of a "it's just the way it is" answer. I'd be curious to hear from the others.
Craig - technically the basemaps come from ArcGIS Online or ArcGIS Enterprise. Depends how you are signing into ArcGIS Pro. If you go to the Map Viewer, all web maps start with a required basemap in WGS 1984 Web Mercator. Same for inserting a new map view in ArcGIS Pro, it adds a default basemap of your organization. If you do not have a basemap when you share a web map from ArcGIS Pro, it throws a 00216: Map does not contain a basemap error message. Not exactly a "why" answer more of a "it's just the way it is" answer. I'd be curious to hear from the others.
