I've noticed that certain sounds don't play when you're looking away from the direction of them. Such as the AWS, which I need not spell out the dangers of. This could be specific to London Commuter, though I could be wrong.
Some of the AWS magnets on the route are faulty, so it's not the sound it's the magnet implementation
No. The AWS can be heard if you look towards the speaker, but doing so has very obvious consequences. As soon as you look away however, you cannot hear it AT ALL.
Yes, I have reported two myself. Maybe you've discovered a separate issue but there are a few known AWS that NEVER sound
