Hi @FredDeNisco ,
I believe the heading option is not appearing because the heading you are referring to is actually a title of a point in your map tour. They are similar but are not technically headings; if they were, it would cause complications in navigation. When turning on the navigation links in the story's design, for example, you would then have a navigation link at the top of your story for every map tour point!
A workaround for this if you really want the heading link, would be to use sidecars instead of map tours. You just wouldn't have those points on the map numbered automatically as they are in a map tour layout. However, you could still configure a map to jump from focusing on a different extents/points for each slide.
This idea of adding headings within map tours has also been requested by other Esri Community users. Please feel free to add a Kudo to this similar idea to the ArcGIS StoryMaps Ideas board if you want to see this enhancement to the product down the line!