Our client report production iOS app freezes when there are a lot of stuffs going on in the app (notifications, background fetch, UIAlertControllers, interactions from user), they couldn't interact with the app and the only way was to kill and restart it. Software updates are the latest and iPad model is recent. However, we've never been able to replicate the issue during testing and development. Does anyone have any idea what could potentially be the issue? Thank you in advance!