FCM notifications not received in Flutter when there is a background handler for the app

Question

I have FCM configuration in my app, and its working fine until I invoke my background handler in the app background running state, I got that

Tried to automatically register plugins with FlutterEngine (io.flutter.embedding.engine.FlutterEngine@7d7493b) but could not find and invoke the GeneratedPluginRegistrant.

but when I tried to register manually using flutterEngine?.getPlugins()?.add(FirebaseMessagingPlugin())

I got that the FCM already registered with this engine, and then the notifications never been received

this is how I call my Background handler:

    if (flutterEngine == null) {
        handler?.let { callbackRawHandle ->
            flutterEngine = FlutterEngine(contextm).also { engine ->
                val callbackInformation =
                    FlutterCallbackInformation.lookupCallbackInformation(callbackRawHandle)
                engine.dartExecutor.executeDartCallback(
                    DartExecutor.DartCallback(
                        contextm!!.getAssets(),
                        FlutterMain.findAppBundlePath(),
                        callbackInformation
                    )
                )
            }
        }
        
    }

Answer 1

The answer is here FCM/GitHub I asked the same question for FCM Developers, And the new update should solve this.