I’d be willing to bet the Blu-ray’s are sending a DTS signal, which the Sonos can’t process. Sonos can only process Dolby Digital or Stereo signals. Some Blu-ray’s have an optional Dolby Digital soundtrack, but you usually have to select it specifically on each disk.

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Or, it’s possible that you need to turn on HDMI-CEC compliance:



https://manuals.playstation.net/document/en/ps4/settings/devicelink.html

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