I'm having the same issue. There does not appear to be a way to get audio to record in the background for longer than 30 seconds.

I can't get the audio to continue recording longer than 30 seconds while in the background. I have 'audio' in my Background Modes set and the recording/mic continues (with the orange pill) after I put the app in the background but only for 30 seconds. Then the app is suspended. How are you supposed to make this work? My app is a real-time transcription app, and I know this works just fine with the Otter app so I know it is possible.