Apple Music AirPlay to HomePod Keeps Stopping

AirPlay from Music on my Mac (Sequoia 15.1.1) recently just keeps stopping after a few seconds.

I start a track.

For some reason (this has always happened) Music decides to play it via my Mac's speaker for a second, then connect to the HomePod. It starts playing on the HomePod, then 3 seconds later it stops. If I press play on the Mac, it plays on the HomePod but it plays the same part of the song again.

Sometimes if I move to the next track it will work (this is what I've been doing for a while), but today it just isn't taking.

I've tried: Power cycling the HomePod, Restarting Apple Music. I've also tried setting the system audio output to the HomePod instead of just setting the Music output to it.

If I AirPlay from my iPhone to my HomePod (original), it works fine. Playing from Mac to it's internal speakers and AirPods works fine.

The Mac and iPhone are on the same network. Mac is wired with 2.5G connection.

Given that this is working fine from iPhone, I think it's a Mac / Music app issue.