Make PlayerControlView work as a standalone component

Porting my app from ExoPlayer to Media3, and have struggled around most of the gaps in the information, and finally have something that works.

I'm down to my last issue to fix, specifically that the next/previous track buttons aren't showing in PlayerControlView. They are showing everywhere else:

• The notification has them, and they work.
• Android Auto works.
• Next/Previous on my car's hardware buttons work.

Given all this, I think would usually assume the player is being build correctly, and it's something else, however, I briefly see the next/prev controls, when the activity loads, until the the player gets connected, then they disappear.,

I did a bit of debugging, and calling hasNextMediaItem() returns true, as does hasPreviousMediaItem() when I ask my mediacontroller if it's got things to play in the list.

I have tried all the usual things like forcing it to show using setShowPreviousButton(true); and setShowNextButton(true); and also setting this in the XML, this also didn't work.

I have tried stripping my player back to the basics, with none of the fancy stuff, still no joy. I'm not doing anything fancy, just a list of MediaItem of audio streams.

I'm now thinking about going back to Exoplayer, and parking Media3, as i've run out of ideas. Hoping someone here might have some ideas on what to look at next.