playbackProgressDidChange not firing? help.

trying to build a progress indicator for playback. I'm calling music.play() - and then listening for 'playbackProgressDidChange' events but not getting any ... here's my code:

export function setupEventListening(music) {
  console.log("setting up event listeners ...")
  music.addEventListener('mediaItemDidChange',(e)=>console.log("mediaItemDidChange called"))
  music.addEventListener('playbackProgressDidChange',(e)=>console.log("playbackProgressDidChange called"))
}

after calling music.play() I do get a 'mediaItemDidChange called' message in the console. But as the song progresses, i never see a "playbackProgressDidChange called" message ...

Any help would be greatly appreciated. Thank you.

chris