QMediaRecorder does not start recording on darwin backend

Mac mini intel core i5, MacOS Sonoma 14.5

When using the darwin backend (via the environment variable QT_MEDIA_BACKEND=darwin), the QMediaRecorder::recorderStateChanged signal does not emit with the QMediaRecorder::RecordingState state, but no errors occur:

"Logitech Webcam C920-C"
Qt::PermissionStatus::Granted
on_pushRecord_clicked() QMediaRecorder::NoError ""
on_pushRecord_clicked() QMediaRecorder::NoError ""
on_pushRecord_clicked() QMediaRecorder::NoError ""
on_pushRecord_clicked() QMediaRecorder::NoError ""
on_pushRecord_clicked() QMediaRecorder::NoError ""
on_pushRecord_clicked() QMediaRecorder::NoError ""
on_pushRecord_clicked() QMediaRecorder::NoError "" 

I am attaching a minimal project for reproduction and result of test_audio_config utility.

Update 0

The problem is caused by the fact that the number of audio channels is not specified before recording starts, and the same problem occurs when explicitly called before recording starts:

audioRecorder->setAudioChannelCount(-1);
// (this call assumes that the number of channels will be selected automatically). 

When explicitly specifying, for example, two channels:

audioRecorder->setAudioChannelCount(2); 

recording starts i.e. The QMediaRecorder::recorderStateChanged() QMediaRecorder::RecordingState signal is emitted.

However, another problem arises. One recording cycle is successful, but if you then start recording again, the following will happen. Immediately after the QMediaRecorder::recorderStateChanged() QMediaRecorder::RecordingState signal, I catch the QMediaRecorder::errorOccurred() QMediaRecorder::FormatError "An unknown error occurred (-12737)" signal and then the QMediaRecorder::recorderStateChanged() QMediaRecorder::StoppedState signal. And this concludes the recording.

Here's the relevant output:

"Logitech Webcam C920-C"
Qt::PermissionStatus::Granted
on_pushRecord_clicked() QMediaRecorder::NoError ""
QMediaRecorder::recorderStateChanged() QMediaRecorder::RecordingState
on_pushRecord_clicked() QMediaRecorder::NoError ""
QMediaRecorder::recorderStateChanged() QMediaRecorder::StoppedState
on_pushRecord_clicked() QMediaRecorder::NoError ""
QMediaRecorder::recorderStateChanged() QMediaRecorder::RecordingState
QMediaRecorder::errorOccurred() QMediaRecorder::FormatError "An unknown error occurred (-12737)"
QMediaRecorder::recorderStateChanged() QMediaRecorder::StoppedState 

Update 1

If I set audio input before each staring of recording and remove after each ending of recording then I get specified problem (QMediaRecorder::errorOccurred() QMediaRecorder::FormatError "An unknown error occurred (-12737)"):

captureSession.setAudioInput(new QAudioInput(this));
//...
audioRecorder->record();

// ...
void onRecorderStateChanged(QMediaRecorder::RecorderState state)
//...
    case QMediaRecorder::StoppedState:
        captureSession.setAudioInput({});

But if I set audio input once before first starting of recording then the problem is gone.

When I use QT_MEDIA_BACKEND=ffmpeg the problem doesn't observed no matter when the audio input is set.

I attach source code for each case.