Fixed!

This wasn’t working on iOS 9.0, but now it works on 9.1.3. I am happy once again. Sadly, it seems to me that it is no longer supported or maintained by the developer, so you might want to think twice about purchasing it. Hopefully they’ll have a new release soon, showing some evidence that they’re still in operation.

Lance J. about Beat On - Advanced Metronome with Training Modes