Wireless audio sync not working

After trying to use Apple TV wireless audio sync several times, it has stopped working at all.

It used to work, at least for a little while, when I would play music from my Apple TV to my Sonos Ones in stereo, while also out of my sound bar through HDMI (all in the same room).

Now even when I run the sync calibration, I get an audio delay of about 300-500ms between the Sonos and the sound bar.

Is there a fix for this?