Fixed: Groove Music buffering music forever, not playing!

This had been driving me mad - Windows 10 on my Surface Go has a competent music player in Groove Music, but it had been misbehaving. What happens is that I start a local (i.e. on my device, on microSD) track playing and I get the animating dots as if it's loading from the Internet. Which it's not, so it should be near instant.

And yet I wait, and wait and wait. The music never starts playing. Groove is stuck. I can select other tracks but they also don't play. What's going on?

The only references to similar problems online pointed me towards an issue with an output device or at least with the sound system in Windows. In other words, Groove Music was looking for... something.

I racked my brains for something which might have changed in my Surface's setup. And then remembered installing MP3 Skype Recorder, which, as it sounds, grabs audio from incoming Skype calls. Moreover, I've noted that this auto-starts when I boot Windows occasionally, meaning that it's always lurking in the background, ready to intercept Skype activity. Could it be this extra audio interception that was confusing Groove Music?

The way to tell, obviously, was to stop MP3 Skype Recorder and (below) to stop it auto-starting in the future (this also helps Windows boot time):

And behold, Groove Music now works just fine. Which is... interesting, to say the least. And doesn't really inspire confidence in the audio subsystems inside Windows. But hey...

Now, don't get me wrong, I'm not criticising MP3 Skype Recorder per se, the culprit might have been anyone one of a number of other audio-intercepting utilities. But I would encourage anyone with Groove Music playback problems to look at their audio stack in terms of installed apps that input or output sound and start eliminating likely culprits.