Bugs fixed in 1.1
Some customers have reported this problem, and have fixed it like this:
"It was the new OS’s change of the side switch being a landscape lock or mute. Changed it BACK to a mute, changed it to full volume (even though it was working with every other app) and then set it back to landscape lock and it brought the sound back."
Another possible cause is AirPlay. If you have selected AirPlay as a destination in another App (e.g. iPod or Movies), that audio destination applies to all Apps. If the AirPlay destination has become unavailable (e.g. being used by some other device), not only will the Fairlight App audio not be heard anywhere, but it may stop altogether until you select an available destination, such as the device itself.