Speech recognition not working on Android 5.1.1 Xamarin

I am trying to use the offline speech recognition engine to detect a phrase to activate a command on my app.

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation, ScreenOrientation = ScreenOrientation.Landscape)]
public class MainActivity : AppCompatActivity, IRecognitionListener
{
    Intent mSpeechRecognizerIntent;

    public override async void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
    {
        Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);


        if (grantResults.Where(x => x == Permission.Denied).Count() == 0)
        {
            SpeechRecognizer speechRecognizer = SpeechRecognizer.CreateSpeechRecognizer(this);
            speechRecognizer.SetRecognitionListener(this);

            mSpeechRecognizerIntent = new Intent(RecognizerIntent.ActionRecognizeSpeech);
            //mSpeechRecognizerIntent = new Intent(RecognizerIntent.ActionVoiceSearchHandsFree);


            mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraCallingPackage, PackageName);
            mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraPreferOffline, true);
            mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraPartialResults, true);
            mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraMaxResults, 5);
            mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraLanguageModel, "en");


            int max = 30000;

            //mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraLanguageModel, this.Resources.Configuration.Locale.Language);
            //mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraPrompt, "test");
            //mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraMaxResults, max);
            //mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraSpeechInputCompleteSilenceLengthMillis, max);
            ////mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraSpeechInputMinimumLengthMillis, max);
            //mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraSpeechInputPossiblyCompleteSilenceLengthMillis, max);

            speechRecognizer.StartListening(mSpeechRecognizerIntent);


        }

        base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    }


    public void OnBeginningOfSpeech()
    {

    }

    public void OnBufferReceived(byte[] buffer)
    {

    }

    public void OnEndOfSpeech()
    {

    }

    public void OnError([GeneratedEnum] SpeechRecognizerError error)
    {
        Debugger.Log(0, "cat", "Speech error: " + error);
    }

    public void OnEvent(int eventType, Bundle @params)
    {

    }

    public void OnPartialResults(Bundle partialResults)
    {
        List<string> matches = partialResults.GetStringArrayList(SpeechRecognizer.ResultsRecognition).ToList();

        Debugger.Log(0, "cat", "Partial Matches are: " + string.Join(", ", matches.ToArray()) + "\r\n");

    }

    public void OnReadyForSpeech(Bundle @params)
    {

    }

    public void OnResults(Bundle results)
    {
        List<string> matches = results.GetStringArrayList(SpeechRecognizer.ResultsRecognition).ToList();

        Debugger.Log(0, "cat", "Matches are: " + string.Join(", ", matches.ToArray()) + "\r\n");
    }

    public void OnRmsChanged(float rmsdB)
    {

    }
}

It works on my android 7.0 phone, but none of the callbacks fire on my android 5.1.1 phone.

Also when I try it on an emulator. It gives the SpeechRecognizerError.Server error.

The emulator also doesn't allow me to download any offline engines.

The Android 5.1.1 phone does have engines downloaded and works for speech recognition with both wifi and data off, but not in my application.

How can I fix this issue?

mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraPreferOffline, true);

this looks to breaking your code, not sure but probably Google is not supporting it.
try to comment this out.
//mSpeechRecognizerIntent.PutExtra(RecognizerIntent.ExtraPreferOffline, true);