I'm playing music from iTunes on my computer, connected to a Yamaha RX-A870 Receiver wirelessly. When I open the MusicCast app on my iPhone and select AirPlay as the source, I see the album and hear the music, but I can't forward, rewind or pause the track. The only thing I can do on the phone is change the volume. The other 'buttons' are dead. I am beginning to think that Music Cast does not work properly with iOS 13.