I have done a little more testing with regards the sound loss. It appears to only happen on my iPhone 13 Pro running the latest 16.0.2 IOS.
I can reproduce this 100% - In Live View, hit Record, hit Stop Record, and clip saves, hit More, hit Album, play the recorded clip = total silence.
In addition anything triggered by a sound event is also silent
This does not happen on my iPad Pro also running latest IOS 15.7, all recordings have sound. I have airdropped recordings from both iPhone and iPad to my iMac (yes Apple fan boi here) Sound on iPad recordings and no sound on iPhone recordings.
Checking through my settings, I can confirm that all detection and notifications and smart settings are exactly the same.
Anyone else have similar equipment can test please?
Jeremy