Audio synchronization between Apple TV HD and HomePod

The audio on my HomePods and TV speakers, connected to an Apple TV HD, is in sync when playing YouTube videos, but is not in sync when playing Amazon Prime Video.

I've confirmed that both the Apple TV and the HomePods software is up-to-date, temporarily removed all devices from power, restarted the WIFI and router and all devices, and reconfigured the audio output to be both TV and HomePod speakers.

Same as before, the audio on my HomePods and TV speakers is in sync when playing YouTube videos, but is not in sync when playing Amazon Prime Video. Any ideas are welcome.