trouble with SKStoreProductViewController and MPMediaLibraryDidChangeNotification

My app uses Apple Music Search to find song and then uses SKStoreProductViewController to let users them buy.

On my test device I correctly see the SKStoreProductViewController how ever I can not seem to actually purchase anything. I see the "buy circle" spin. my productViewControllerDidFinish: delegate is called how ever I never recieve MPMediaLibraryDidChangeNotification

I check my purchase history on my mac using iTunes, and on my test devices. Seems like they do not get purchased or downloaded?

Here is my notification registration code

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(mediaLibraryDidChangeNotification:)
                                                 name: MPMediaLibraryDidChangeNotification
                                               object:nil];
    [[MPMediaLibrary defaultMediaLibrary] beginGeneratingLibraryChangeNotifications];

I would like to know when/if the purchase was completed and when/if the song was downloaded

based on other threads I think the issue might be that SKStoreProductViewController might be disabled when you are working in your development or testFlight enviroment. Is that true? If so any idea how I can test my code with out releasing it first?

Kind regards

Andy