WhatsApp audio messages won't play (other sound does) [Mac]

[tapetv]

With Firefox 77.0.1 (Mac). I'm not able to hear audio-messages send to me with WhatsApp (web-application).
It's an Oog-vorbis-file afaict. I remember similar audio-problems some years ago: YouTube or Vimeo would play, but e.g. Spotify wouldn't.
Anything I can do to solve this?

[therube]

Have a sample file that doesn't work for you that you can post somewhere?

[tapetv]

https://tapetv.stackstorage.com/s/q0G7Touvl1m2I20

This does play in Chrome, but not in Firefox, even in safe mode.

[therube]

Plays on my end, Windows, XP & SeaMonkey, Win10 & FF Quantum.

Download file
Drag in browser
(very clear) audio playback

Seemingly should be working on Mac too, HTML5 audio and video in Firefox.

(And yes, it is ogg (opus).)

[tapetv]

Here it does not play: not straight from the link I posted, nor drag and drop on Firefox. What's getting in the way here?

[therube]

Maybe see what this page shows, Legacy YouTube HTML5 Video Tests.

[tapetv]

Just back to correct my own mistake: It was due to the fact that mono audio (meaning 1 channel) plays over my center-speakers in my 5.1 surround studio. And most of the time, that system is turned off (as in: I won't do surround today