HASS.Agent: TTS/media playback silent when Windows default audio format is "Dolby Atmos for Home Theater"

I've been beating my head against the wall over this for the last couple of days and finally discovered why I was unable to get TTS announcements on my main PC through Hass.Agent. Full disclosure, Claude AI was a big help in determining why my TTS actions were executing successfully in HA, but with no results. Since there is no place on the HASS.Agent Github to post the issue, I guess the correct spot is on this forum? Here is the summary of the issue:

  • Windows.Media.Playback uses WASAPI shared mode
  • When default audio format is set to "Dolby Atmos for Home Theater", WASAPI shared mode cannot mix standard PCM audio, resulting in completely silent playback
  • State correctly reports Playing → Paused with correct duration, giving no indication of failure
  • Workaround: changing default format to standard PCM (e.g. 24-bit 48000 Hz) restores audio
  • Fix suggestion: HASS.Agent should initialize audio using WASAPI exclusive mode or a spatial audio-aware rendering path.

Thanks.

EDIT: My mistake, it seems I was looking at the wrong Github page (The Hass.Agent situation seems a little confusing). I will post on the Github but leave this here in case it's useful to anyone else or someone has a suggestion.