AKFFTTap stops generating data after some time

Question

I'm using AudioKit for a recorder app, and I added a AKFFTTap to the AKMicrophone for drawing a custom audio waveform. This all works well, but after several recordings, or after some time passes with the app recording screen open, the FFT data suddenly becomes all 0. I know the mic is working and the gains don't change, since the recorded file contains the expected audio. It seems like just the FFT tap stops working all of a sudden.

Anyone have any idea why this is and how can I solve it?

Thanks!