Thanks for the reply. The story map seems to be working as of yesterday (August 6th). I was able to successfully unpublish and then republish, then it worked. (I tried this before but this was the first time it worked)
The express map with the attachments was not a recent addition, that was done in early June. Each point had a single picture but they seem to be gone (I did not remove the images).
At the time I had the issue, I uploaded the final video (50 in total) to the story map. At the time I used "Upload" but this seemed to slow down the loading time (total story map size was 1,569.17MB), so I switched to linking Youtube Videos (brought the total story map size down to 50 MB). Then the issue of being unable to publish, unpublish, duplicate, or delete occurred.