@aaron.galit - clarifying question... is she LINKING to the images (via URL) or downloading images into the App Lab assets?
I have seen students download the images into assets, put them in their app, and then delete the images from the assets (to kind of clean up their workspace), but that means that App Lab will not be able to retrieve those images again (once they are deleted from assets). The student needs to keep the images inside the assets space.
That is my first suggestion, I hope that works! If not, send the code my way and I can take a stab at it!