Uncomment the basemap's load method from the following code: var sta = basemapOrto.load();Both basemaps are shown in the widget.This issue happens precisely with a custom basemap and in a scene view.Basemap API suggests the method must be called by the developer when accessing a resource that will not be loaded in a View. Refer to the link below:<a href="https://developers.arcgis.com/javascript/latest/api-reference/esri-Basemap.html#load" target="_blank">https://developers.arcgis.com/javascript/latest/api-reference/esri-Basemap.html#load</a>