Google+ app does not launch live video hangout Device: Nexus 4
Android: 4.3

When there is a live video hangout, the Google+ app makes a button available on the post called Watch Hangout On Air. However when I press it, YouTube launches the What to Watch screen, but the hangout video isn't in the list and nothing auto-plays. 

The live Hangout is occurring. I can watch it on my laptop by using the same G+ post to launch it as I'm trying to use from my phone inside the app. 

I've cleared the App Defaults for both the Google+ app and for YouTube. The Hangouts app has no defaults set yet.  My apps are all the latest versions.

I've used the back button in the YouTube app and have backed right out of it altogether, just to check that the live hangout video isn't hidden behind another screen activity. 

Does anybody have any suggestions?
Not sure if this is it. From Google Support:


  The YouTube app won't work with Hangouts On Air. So if you use
  Hangouts On Air, your viewers will only see the video call, not your
  playlist or the videos.