Uv_queue_work doesn't run callback_method in node addon (C ++)

I am creating a node addon in C ++ and I want to be able to make callbacks from other threads. To try it I am doing the following test using uv_queue_work and Nan. If I call the Hello function, it should start a new thread for the firstMethod method, and when it ends, call the next "callbackMethod" method on another thread where I would make a Javascript callback. But for some reason, it runs the first method and doesn't run the second.

This is my code.

void Hello(const v8::FunctionCallbackInfo<v8::Value>& args) {
    v8::Isolate* isolate = v8::Isolate::GetCurrent();
    v8::HandleScope scope(isolate);
    v8::Local<v8::Function> callback;

    callback = args[0].As<v8::Function>();

    ListBaton* baton = new ListBaton();
    baton->callback = new Nan::Callback(callback);

    uv_work_t* req = new uv_work_t();
    req->data = baton;
    uv_queue_work(uv_default_loop(), req, firstMethod, callbackMethod);
}

void firstMethod(uv_work_t* req) {
    std::cout << "Entering PRE thread" << std::endl;
    sleep(1);
    std::cout << "Leaving PRE thread" << std::endl;
}

void callbackMethod(uv_work_t* req, int status) {
    v8::Isolate* isolate = v8::Isolate::GetCurrent();
    v8::HandleScope scope(isolate);
    if(!isolate)
    {
        std::cout << "Isolate was null" << std::endl;
        isolate = v8::Isolate::New();
        isolate->Enter();
    }
    ListBaton* data = static_cast<ListBaton*>(req->data);

    v8::Local<v8::Value> argv[2] = {
            v8::Undefined(isolate),
            v8::String::NewFromUtf8(isolate,"WORLD")
    };


    std::cout << "Sending callback" << std::endl;
    data->callback->Call(2,argv);
}
void init (v8::Handle<v8::Object> target) {
    NODE_SET_METHOD(target, "hello", Hello);
}

NODE_MODULE(HelloNan, init);

      

        
        
        
      

    

If you guys could help me with this, I would really appreciate ...