On Mac, capture button records built-in mic instead of audio device input

[GuitarML]

When the "Start Capture" button is clicked, it should record a stereo wav file, where the left track comes from Channel 1, and the right track comes from Channel 2. However, on Mac, the default recording input when using the Start Capture button is the internal microphone (observed on MacBook Air, Big Sur OS, using Tracktion Waveform DAW). This occurred even when the DAW was using the connected ASIO device. When the "Train Tone" button is clicked and this wav file is selected, the result after training is a tone file that has no effect on the input sound (will show 100% training accuracy), because Channel 1 and Channel 2 recordings from the microphone are the same.

This feature works as expected on Win10, Reaper DAW.

Acceptance Criteria:
That the "Start Capture" feature captures both Channel 1 and Channel 2 in the stereo wav file on Mac.