HomePod stereo pair volume out of sync.

I have a stereo pair of full-sized HomePods that lose volume sync every so often when they're connected to my AppleTV (4K 3rd generation). Seems to happen every few months.

Issue: Can't mute one of them, the volume at which it chooses to remain fixed varies from failure to failure.

The HomePods are the second-latest generation as of Sept-2023.

Solution I found, your mileage may vary:

1. AirPlay video from the Apple TV app (on iPhone, iPad, etc.) to the misbehaving AppleTV & stereo pair.
2. Unplug the one misbehaving HomePod. Wait 30 seconds. Plug it back in.
3. Wait. Wait. Wait.
4. While AirPlaying from your i-device, the sound will suddenly come back, be in sync, and sound a lot better than it did before. No idea what's going on with sound degradation.
5. Turn off the AirPlay stream. This causes the AppleTV to switch back to its programming, including its audio being sent to the formerly misbehaving audio pair.

That did it for me - this time at least. Good luck.