Hello CharlieXrayDelta, and welcome to the Apple Support Community.
Since Netflix, Apple TV+, Prime Video, and YouTube TV all work correctly with your Apple TV 4K and HomePod mini stereo pair, the issue is unlikely to be with AirPlay, tvOS, or your HomePod setup. It appears to be specific to the Max (HBO Max) app.
Here are a few steps you can try:
- Restart your Apple TV and both HomePod minis.
- Make sure tvOS and the Max app are fully up to date.
- Go to Settings > Video and Audio > Audio Output and temporarily switch from the HomePod stereo pair to your TV speakers. If Max works normally, this helps isolate the issue to the app’s interaction with the HomePod audio output.
- Delete and reinstall the Max app, then sign in again.
- If the problem only affects Max while all other streaming apps work correctly, it’s likely an app-specific compatibility issue that should be reported to Max Support.
The information you read on Reddit regarding the Premium subscription is not an Apple requirement. Audio playback through AirPlay or HomePod should not depend on the subscription tier alone.
Helpful links:
Use HDMI ARC or eARC with your Apple TV 4K - Apple Support
Change audio settings on Apple TV 4K - Apple Support
Could you let us know whether the issue affects audio only, video only, or both? Also, does Max work correctly if you use your TV speakers instead of the HomePod stereo pair? That will help determine whether this is an app-specific audio routing issue.
Please let us know the outcome.
Your feedback may also help other members of the Apple Support Community experiencing the same issue.
🙏🏻
Have a great day.
And one more thing…
Never forget to think different.