Set your trigger to parallel. That should fix the problem of it not playing.
Also, I noticed the script affecting system sounds too. Or if I have music playing on a map it'll treat it in the same way as emittance and have the sound go lower in one side if I go too far from the middle.
I'm a bit conflicted. One the one hand, it's quite visually cool to make bodies of water that the player can interact with by going into it. However obscuring the player character from a gameplay perspective is pretty bad. Hmm... There's the option to make the area around the player visible, but then that kind of defeats the purpose of submerging them.