If changes are made to a Story Map Journal application after panel images are saved when the application is private and then shared publicly, tokens are appended to the images when the application is public-facing, resulting in broken images after the tokens expire.
Option 1: Replace the images while the application is still public-facing. Option 2: Remove '?token=<Token>' from the JSON of the application via ArcGIS Online Assistant. Option 3: Immediately share the application publicly before adding any photos to the panel.