iOS7: AccessibilityLabel on button does not show when set as a leftNavButton / rightNavButton

Description

I am using accessibilityLabel with a button that I then put as a leftNavButton or rightNavButton on a window. The problem is that I cannot get the accessibilityLabel to show (using VoiceOver on the device or the accessibility inspector in the simulator). If I do not set the button as the leftNavButton or rightNavButton it works.

Test Code

var win = Ti.UI.createWindow({

  backgroundColor:'#ffffff',

  title: 'Products'

});

var button = Ti.UI.createButton({

  accessibilityLabel: 'Send screen to Airplay',

  title: 'CLICK'

});

win.setRightNavButton(button);

var nav = Ti.UI.iOS.createNavigationWindow({

  window: win

});

nav.open();