Some problem here. Completely removing the app and then reinstalling it also seems to keep the user's decision.

"Reset Location and Privacy" didn't work for me

In my tests it seems that the system is persisting a status per app, even if removed and reinstalled. On a real device, which had tracking globally disabled, our app received the the "restricted" status. Obviously in this scenario the prompt cannot be shown. Then after globally enabling tracking (aka "Allow app to request to track"), the app asked once via the ATT prompt. Afterwards we were never able to get a different status then "accepted" or "denied", even after removing and reinstall the app. Also "Reset Location and Privacy" in "Settings -> General -> Reset" didn't reset this status. If everyone found a way to reset the status this would be really helpful.