NullReferenceException while disposing WasapiLoopbackCapture

[pedroivobraga]

I have a MixerProvider capable of mixing loopback and microphone input, with the microphone recording being optional. However, I'm experiencing an intermittent issue when disposing of WasapiLoopbackCapture.

Into my dispose method, I'm getting the bellow exception:
System.NullReferenceException: Object reference not set to an instance of an object.
at System.Runtime.InteropServices.Marshal.ReleaseComObject(Object o)
at NAudio.CoreAudioApi.AudioClient.Dispose()
at NAudio.CoreAudioApi.WasapiCapture.Dispose()
at EswLinphoneClient.Media.AudioMixerProvider.Dispose

Dispose method:

      if (!disposedValue)
      {

          if (disposing)
          {
              _mixerProvider.RemoveAllMixerInputs();

              foreach (var source in _mixers.ToArray())
              {
                  source.Buffer.ClearBuffer();
                  source.Input.Dispose(); //THIS DISPOSE IS CAUSING THE ERROR
              }

              _mixers.Clear();

              _silentPlayer?.Dispose();
              _timerLoopbackChecker?.Dispose();
              _timer?.Dispose();
              _device?.Dispose();
          }

          disposedValue = true;
      }

Do you have any idea that what could be causing such issue?