Broadcast upload extension randomly fails, not starting and killing

So the main idea is: my broadcast upload extension making video of phone screen and when it finishes it saves video into directory. When I am starting extension it works well and saving video. It can make video during 30 minutes and longer. But for some reason it can be randomly killed after few sonds of work even few minutes without any error being displayed. I don't know what what is the problem?. Maybe somebody can help me with that? It happens on iOS 13 and iOS 12.