Hi Lauren,
Very sorry about the issue with Story Map Shortlist Beta. Several people have reported a similar issue too (see; Shortlist Storymap has deleted most of my content ) and it is frustrating because we don't want you to lose your work. We are trying to see all the steps that might cause this.
We have seen this happen if people have gone into the web map called "Shortlist Builder" that the Shortlist stores its places in to try and edit the places in that map directly, or if you edit that map to add supporting layers etc while the Shortlist Builder is open in another browser tab. or if you make a copy of a Shortlist app (using a tool like ArcGIS Online Assistant) and then try and make edits to both of your Shortlists (because those edits overwrite each other), but that doesn't explain all the cases where we have heard about it happening, so we are very keen to understand what is going on.
If you are willing to give it another try, in the 1 March 2017 release we added a new authoring option called ''As Is" where the Shortlist reflects the place content that you store, edit and maintain yourself in a web map, instead of maintaining and editing the places in the Shortlist Builder. With this workflow the Shortlist app just displays the places defined in that web map. This may not suit your needs but it can be more convenient if you want to manage your places in your GIS or web map. Because it doesn't use the Builder to add the images to places, it does require that you are able to reference your images via URLs specified as field values in the layer containing your places.
Rupert
