Playback showing unexpected frames on iOS

My daughter has been loving iStopMotion for iOS, but she’s seeing odd issues in a movie playback that we can’t figure out. As she plays the movie, frames from other parts of the movie are inserted in the transitions. Sometimes the frame is a live capture of the camera at the moment.

Not sure of a better way to describe it, so let me know if there’s additional information I can provide

Note that it doesn’t seem to affect the rendered movie. Just the playback within the app.