Flutter Provider Consumer Doesn't Update With Change / Image Picker with provider

Question

im trying to make my own image/file picker by using photo manager package and provider package. I was able to successfully take photos and videos in the device gallery and create thumbnails. I covered the thumbnails with gestureDetector and add the clicked asset to the provider state in Uint8List format. I made consumer transactions where the added images will be displayed, but the consumer does not update on change. Here my codes;

child: MultiProvider(
                      providers: [
                          ChangeNotifierProvider(create: (BuildContext context) => HoldPickedAsset()),
                    ],
                    builder: (context, Widget){
                      return GestureDetector(
                        onTap: (){
                          var insert = Provider.of<HoldPickedAsset>(context, listen: false);
                          if(asset.type == AssetType.image){
                            insert..insertToLists(Posts(type: "1", urlPath: snapshot.data));
                          }else if(asset.type == AssetType.video){
                            insert..insertToLists(Posts(type: "3", urlPath: snapshot.data));
                          }else if(asset.type == AssetType.audio){
                            insert..insertToLists(Posts(type: "4", urlPath: snapshot.data));
                          }
                        },
                          child: Image.memory(
                            snapshot.data!,
                            fit: BoxFit.cover,
                          ),
                      );
                    }
                    ),

and my modal;

class HoldPickedAsset extends ChangeNotifier{
  var postStates = [];
 insertToLists(pos.Posts posts){
  postStates.insert(0, posts);
  notifyListeners();
 }
 removeFromLists(index){
  postStates.remove(index);
  notifyListeners();
 }
}

and lastly the consumer part;

MultiProvider(
      providers: [
                ChangeNotifierProvider<HoldPickedAsset>(create: (BuildContext context) => HoldPickedAsset()),
              ],
        child: Consumer<HoldPickedAsset>(
        builder: (context, state, widget) {
          var lastPost = state.postStates;
          print(lastPost); 
          }
         )
        ),

when I run this code, it just prints an empty list to debug console once but doesn't print anything again on change... Thanks in advance for your help :)