Mvc6 regular binder model does not fire

I'm trying to figure out model binding in current mvc6 (Visual Studio 2015 release candidate). This is my code looks like this:

public class MyObjectModelBinder : IModelBinder
{
    public Task<ModelBindingResult> BindModelAsync(ModelBindingContext bindingContext)
    {

        if (bindingContext.ModelType == typeof(MyObject))
        {
            var model = new MyObject();
            return Task.FromResult(new ModelBindingResult(model, bindingContext.ModelName, true));
        }
        return Task.FromResult<ModelBindingResult>(null);

    }
}

      

        
        
        
      

    

Registration in startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc().Configure<MvcOptions>(options =>
    {
        options.ModelBinders.Add(typeof( MyObjectModelBinder));
    });
}

      

        
        
        
      

    

My controller:

[HttpPost]
public void ReceiveMyObject([FromBody] MyObject x)
{

}

      

        
        
        
      

    

I don't care that I am actually creating an object from the input, what worries me is that when I debug, I see the controller start up (with x being null), but the bind function is not called. Any ideas on what is wrong here?

[EDIT: this has already been updated] Also note that I've already seen What is the correct way to create custom model bindings in MVC6? but the answer in this post is either wrong or outdated as the example provided does not implement the current IModelBinder.

thank

EDIT: This is the javascript code used to start the controller:

function sendMessage(i) {
    $.ajax({
        type: 'POST',
        url: 'myurl',
        data: data,
        contentType: 'application/x-www-form-urlencoded',
        dataType: 'json',
        success: function (data) { console.log(data) }
    });
}