Something that isn’t on their setup guide.
I’ve found that in order to get my audio working. I need to have the sensors powered off, and the apps (Sensorware & GarageBand) both force closed. I can then turn the sensors on, fire up the sensorware app, then they recognise and connect automatically. From there I can fire up GarageBand and I get the audio through either my bluetooth headphones or through the phone speakers.
Anything other than that order doesn’t get me audio unfortunately.