@jdipietro - that sounds frustrating for that student! She sounds super detail orientated which is awesome, but I am sure this feels like a set-back.
I have seen similar detail orientated students "delete" assets from their folder in a project. They do it to clean up the space and make images easier to find, but having those assets in the folder is what makes them accessible to app lab when the app loads. Do you think she did this accidentally?
She could try version history (top right hand corner), but if she deleted the assets, I don't think they will restore which means she will need to re-upload them... hopefully it will be a "lesson learned" moment, though.
If that didn't happen, I would test out reloading them on a mini-scale (2 at a time), closing the program, and re-opening, just to see that indeed it is working as intended. If you still run into issues, add a link to the app here and we can look at it!