>what i can't understand is why in iPhone / iPad emulator works
The simulator is not an emulator, and is only trusted to test your app's basic functions/UI flow. It would be pointless, as well, to worry now about what one may or may not do since you have evidence the app fails device support.
If you can get logs, crash reports etc. via TestFlight, use those as actionable items, along with your own device testing.
Note this from the simulator troubleshooting guide:
Simulator APIs don’t have all the features that are available on a device. For example, the APIs don’t offer:
- Receiving and sending Apple push notifications
- Privacy alerts for access to Photos, Contacts, Calendar, and Reminders
- The
UIBackgroundModes
key - Handoff support
In addition, Simulator doesn’t support the following frameworks:
- External Accessory
- Media Player
- Message UI
- In UIKit, the
UIVideoEditorController
class
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Note this is not an offer to troubleshoot 3rd party tools, etc. See their support sites/forums/FAQ for details on working with their products.