Same problem here, I think the problem is the simulator doesn't know which live activity to update for the given payload.

It's not possible with the current iOS, you will need to send a push notification to update the live activity.

Same problem here, seems no way to detect Sleep Mode

On iOS only .currentProcessIdentifier is available, which gives only logs for current session.

When starting the live activity you will get an error message if system fails to start the live activity. There's no way to use Xcode to preview Live Activity yet, hope Apple adds it soon.

Try running on real iOS device instead of simulator

Still experiencing this issue on iOS 16.6. Tapping "Keep" -> "Deliver Immediately" doesn't upgrade the push permission and still stuck in delivery quietly.

Seems fixed now