flutter - Native Ads wont load & show and also it's event callback not showing anything

While waiting for official Admob's Native Ads for a flutter, I try to integrate it using 3rd party plugin.

I try using a plugin that claimed can show Admob's Native Ads here.

However, the native ads wont load & show on Android Devices (iOS not yet tested).

The event callback also not showing anything.

I have submitted an issue here, but I think the author may be busy, so I post also here.

Below are my codes:

For Initialization:

class HomeScreen extends StatefulWidget{
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> with AfterLayoutMixin<HomeScreen> {

  @override
    void initState() {
      // TODO: implement initState
      super.initState();      
      NativeAds.initialize();
      ...
    }

For NativeAds placement is under below structures:

@override
Widget build(BuildContext context) {
  return Stack(
    children: <Widget>[
      Scaffold(
        appBar: AppBar( .. ),
        body: OfflineBuilder(
              connectivityBuilder: (BuildContext context, ConnectivityResult connectivity, Widget child) {
                  ...  
                  child: NestedScrollView(
                      headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) { ... }
                      body: RefreshIndicator(
                        backgroundColor: Pigment.fromString(UIData.primaryColor),
                        color: Colors.white,
                        onRefresh: () => homeBloc.init(),
                        child: ListView(
                          children: <Widget>[
                            Row(
                            ...
                              ListView(
                                physics: NeverScrollableScrollPhysics(),
                                shrinkWrap: true,
                                children: <Widget>[

                                ...


                                SizedBox(
                                  width: double.infinity,
                                  height: 320,
                                  child: NativeAdView(
                                    onParentViewCreated: (_) {
                                      print("sinative create.....");
                                    },
                                    androidParam: AndroidParam()
                                      ..placementId = "ca-app-pub-xxx" //my admob
                                      ..packageName = "com.apps.myapp"
                                      ..layoutName = "native_ad_layout"
                                      ..attributionText = "AD",
                                    iosParam: IOSParam()
                                      ..placementId = "ca-app-pub-3940256099942544/3986624511" // test
                                      ..bundleId = ""
                                      ..layoutName = ""
                                      ..attributionText = "SPONSORED",
                                    onAdImpression: () => print("native is show"),
                                    onAdClicked: () => print("onAdClicked!!!"),
                                    onAdFailedToLoad: (Map<String, dynamic> error) => print("native is error ==> $error"),
                                  ),
                                ),                      

                                ...

                                ...

Any Idea?

Thanks In Advance...

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