Thanks Doug. I appreciate the extra eyes.
I just tried to embed a podcast recording from my Course Files into a Page.
Same result. No playback button.
I then though maybe I need to upload the mp3 file from my computer and embed it like @melodyc_lam mentioned they tried with success, but it still created the same result -- a media player without a play button. See below screenshot.
When these no-play-button interfaces appear, I can get the audio to play. In fact, until the play button reappears, I included a tip of clicking the audio player once then click using the spacebar to begin playback, but that's not very intuitive especially when videos are working just fine.

@AkosFarago I am wondering if this is issue is related to embedding an mp3/audio file only? My video files in other parts of my course are looking great. Very nice play buttons there.
However, for my quizzes where I've voice-recorded the questions (since immersive reader doesn't extend into the classic quiz tool) and in my colleagues courses (for example, one of our mandarin teachers' courses where students listen to a sentence and transcribe what they hear), the new media player is causing some challenges.
Do you think it might be something to do with audio files?
Thanks for the extra eyes on this.
PS -- although I haven't checked this out yet, @AkosFarago I've heard from other colleagues that YouTube ads now appear in CanvasStudio videos. Sorry -- don't want to mix the topics here.