Hmm, that happens to my friend too in her iTouch. When she imports a video, the app just exits before she even gets to the section where we put the caption. She told me about it and I tried this: Close every running app in the background, or soft-reset the itouch. Go straight to IG, avoid the filters, and do it fast. Like, if possible, don't take time putting caption to it. Then upload. Maybe it'll work on ipad mini too. When exactly does the app exit?