My Playbar is connect via Toslink optical cable, with a sub connected via Ethernet and two wall mounted Play 5's connected by wireless. Anyhow, I'll switch to my kids favourite show, say Octonauts on Netflix, and sometimes the audio drops out, but it only happens on some shows. At first it was a mystery, but now I fire up the iPhone app and it says "Unsupported audio type" or something like that, and I disable the speech booster, dismiss the alert, and then enable the speech booster again, dismiss the alert, and all good. It's worth noting that Netflix is running via the app that comes with the Hisense 75" TV and I've installed no software updates to the TV, nothing has changed, apart from Sonos updates that have come through recently, about two of them.
Sonos system has been awesome since purchase, but noticed this started happening after a recent software update in the last month or so, and is super annoying and chipping away at the great Sonos experience that I had been enjoying, so please get onto this and fix the software bug causing it.