I've been having this problem for years and hoping someone can help.
I have a soundbar connected via HDMI-ARC to my KS7000, and on live TV and my Nintendo Switch the TV outputs audio without problem. However, there are a couple of situations where it will suddenly switch back to TV speakers, or get completely stuck on "Receiver" mode but not outputting audio (requiring the TV to be unplugged):
When my PS4 switches display modes (to HDR etc) when starting a game, there's a 50% chance audio will be lost sometimes requiring the PS4 or the TV to be powered down before the output can be changed back.
Occasionally between adverts shown on catch-up TV apps.
More rarely, between auto-play trailers on the Netflix app (which can't be turned off).
I've noticed that in each of the trigger situations (even when it's working), there's an audible click which I'm assuming is the TV starting/stopping the audio stream to the soundbar?
I also tried using optical out and encountered similar problems.
I've done several factory resets, the firmware is up to date and it's happened on 3 different soundbars (LG, Sony and Cambridge Audio).
Has anyone experienced this issue or can offer a solution?
I recall reading a post (possibly on this forum) over a year ago saying that Samsung TVs have a problem with the HDMI handshake (something about it not always doing it in the required time?), although I can't find any evidence of this post now. Could this be related?