Cannot scan any bluetooth device on all Android versions

Question

I'm working on A2DP and GAT bluetooth profile. I need get all available A2DP bluetooth devices around bluetooth application.

However, I didn't scan any low energy bluetooth device or classic bluetooth device by using startDiscovery() or startLeScan() API so far.

I set enough permission in the Android Manifest file as below:

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />

I also pulled and run Google's origin sample:

https://github.com/android/connectivity-samples/tree/master/BluetoothLeGatt

But, it didn't work

Here is my code by using startDiscovery API

    public void searchDevices(OnSearchDeviceListener listener) {

    checkNotNull(listener);
    if (mBondedList == null) mBondedList = new ArrayList<>();
    if (mNewList == null) mNewList = new ArrayList<>();

    mOnSearchDeviceListener = listener;

    if (mBluetoothAdapter == null) {
        mOnSearchDeviceListener.onError(new NullPointerException(DEVICE_HAS_NOT_BLUETOOTH_MODULE));
        return;
    }

    if (mReceiver == null) mReceiver = new Receiver();

    // ACTION_FOUND
    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    mContext.registerReceiver(mReceiver, filter);

    // ACTION_DISCOVERY_FINISHED
    filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
    mContext.registerReceiver(mReceiver, filter);

    mNeed2unRegister = true;

    mBondedList.clear();
    mNewList.clear();

    if (mBluetoothAdapter.isDiscovering())
        mBluetoothAdapter.cancelDiscovery();
    mBluetoothAdapter.startDiscovery();

    if (mOnSearchDeviceListener != null)
        mOnSearchDeviceListener.onStartDiscovery();
}

I'm not sure, Has the Google updated the bluetooth framework?

If anybody know this issue, please help me. Thank in advance.