Android Wear custom notification not showing activity

I'm working on a custom notification for Android Wear that should display a custom activity when the notification is swiped upwards. The notification is displayed, and even the wearable features (like the background and custom size) are visible, however the activity is never loaded nor displayed.

Also, MainActivity and PlaybackNotificationActivity should both write a message to the log when they're created. MainActivity writes the message, but the latter doesn't.

What could be the problem?

MainActivity.java

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        new NotificationBuilder(this).showNotification();
        Log.e("MainActivity", "Reached");
        finish();
    }
}

NotificationBuilder.java

public class NotificationBuilder {
    private final Context mContext;

    public NotificationBuilder(Context context) {
        mContext = context;
    }

    public Notification buildNotification() {
        Notification.Builder builder = new Notification.Builder(mContext)
                .setContentTitle("Title")
                .setContentText("Content text")
                .setSmallIcon(R.mipmap.ic_launcher);

        Intent playbackIntent = new Intent(mContext, PlaybackNotificationActivity.class);

        PendingIntent playbackPendingIntent = PendingIntent.getActivity(
                mContext, 0, playbackIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        Notification.WearableExtender extender = new Notification.WearableExtender()
                .setBackground(BitmapFactory.decodeResource(mContext.getResources(), R.mipmap.ic_launcher))
                .setCustomSizePreset(Notification.WearableExtender.SIZE_MEDIUM)
                .setDisplayIntent(playbackPendingIntent);

        builder.extend(extender);

        return builder.build();
    }

    public void showNotification() {
        Notification notification = buildNotification();

        NotificationManager manager = (NotificationManager)
                mContext.getSystemService(Context.NOTIFICATION_SERVICE);

        manager.notify(1, notification);
    }
}

PlaybackNotificationActivity.java

public class PlaybackNotificationActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_playback_notification);

        Log.e("NotificationActivity", "Reached");
        Toast.makeText(this,  "Toast", Toast.LENGTH_SHORT).show();
    }
}

It turns out that the emulator for Android Wear is to blame, it works perfectly on a physical smartwatch but not on the emulator.