AudioTrack UpdatePositionListener not working for MODE_STATIC

This is a follow up to this question:

End of playback detection in AudioTrack is not working

AudioTrack initialization and relavent code are in this function:

    // function that plays out the audio through the audio hardware
    void playSound(){
//         final AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
//                sampleRate, AudioFormat.CHANNEL_OUT_MONO,
//                AudioFormat.ENCODING_PCM_16BIT, generatedSnd.length,
//                AudioTrack.MODE_STATIC);

        final AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                sampleRate, AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, generatedSnd.length,
                AudioTrack.MODE_STREAM);
        audioTrack.setNotificationMarkerPosition(generatedSnd.length/2);
        // audioTrack.setNotificationMarkerPosition(1);
        audioTrack.setPlaybackPositionUpdateListener(new AudioTrack.OnPlaybackPositionUpdateListener() {
            @Override
            public void onPeriodicNotification(AudioTrack track) {
                // nothing to do
            }

            @Override
            public void onMarkerReached(AudioTrack track) {
                Log.d("MY LOG", "Audio track end of file reached...");
                //bitPatternValTextView.setText("End of play");
//              inSituPlaybackCompleted = true;
                // idx = 0;
                // btnVolumeUp.setEnabled(true);
            }

        });

        audioTrack.write(generatedSnd, 0, generatedSnd.length);
        audioTrack.play();

    }  

This function has been called elsewhere (in the same MainActivity class) elsewhere:

    public void btnVolumeUp_click(View view){
        textview.setText("Volume Up Button Clicked");
        genTone(0.0);
        genTone(1.0);
        genTone(0.0);
        genTone(0.0);

//          genTone(1.0);
//          genTone(1.0);
//          genTone(1.0);
//          genTone(1.0);


        // Use a new tread as this can take a while
//      final Thread thread = new Thread(new Runnable() {
//            public void run() {
//                // genTone();         // this line is left here for my record only
//                handler.post(new Runnable() {
//
//                    public void run() {
//                        playSound();
//                    }
//                });
//            }
//        });
//        thread.start();
        // btnVolumeUp.setEnabled(false);

        playSound();    // TROUBLESHOOTING

    }  

Currently the playSound() has been called in the same UI thread, but the commented section shows how it had been called in a separate thread as well. (the idea for using the UI thread came from this comment which says try MODE_STREAM if using a separate thread). However, whether using a new thread or the UI thread, the setPlaybackPositionUpdateListener() does not seem to be working, as onMarkerReached() is not being called. Currently I generate my own audio samples (that is, I am not playing a file) and the whole audio (at most around 10 sec long) will have been generated before the playback starts (which makes me think I should be using MODE_STATIC since I am not doing any streaming, and to be honest I don't think I know how to use MODE_STREAM properly at this point anyway). In my code, if I do not change anything else and just change MODE_STATIC to MODE_STREAM in the AudioTrack initialization, the onMarkerReached() function seems to work. However, I would want it to work for MODE_STATIC for the reason stated above.

Why isn't onMarkerReached() being calle dfor AudioTrack MODE_STATIC and how do I fix it? Alternatively, all I really want to do is able to find out when the AudioTrac playback stops. If there are alternate ways to do it then those answers are welcome as well.