Can't generate new routes in Sonata Admin - symfony

Question

I'm struggling to make a custom action in Sonata Admnin, I followed the guide Sonata documentation and tried to copy the code from another of my projects where it worked fine.
My Admin class is:
namespace BlogBundle\Admin;
use AppBundle\Form\Type\FacebookType;
use Sonata\AdminBundle\Route\RouteCollection;
use Sonata\CoreBundle\Form\Type\BooleanType;
use Symfony\Component\Form\Extension\Core\Type\CheckboxType;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Sonata\AdminBundle\Datagrid\ListMapper;
use Sonata\AdminBundle\Form\FormMapper;
use Sonata\AdminBundle\Admin\AbstractAdmin;
use Knp\Menu\ItemInterface as MenuItemInterface;
use Sonata\AdminBundle\Admin\AdminInterface;
class PostAdmin extends AbstractAdmin
{
protected function configureRoutes(RouteCollection $collection)
{
$collection->add('facebookAction');
}
protected function configureListFields(ListMapper $listMapper)
{
$listMapper
->addIdentifier('id',TextType::class,[
'label' => 'entity.post.id'
])
->add('active',BooleanType::class,[
'label' => 'entity.post.active'
])
->add('_action', null, [
'actions' => [
'show' => [],
'edit' => [],
'delete' => [],
'facebook' => [
'template' => 'BlogBundle:Admin:empty.html.twig'
]
]
]);
;
}
//...
}
Service declaration:
services:
admin.blog.post:
class: BlogBundle\Admin\PostAdmin
arguments: [~, BlogBundle\Entity\Post, BlogBundle:PostAdmin]
tags:
- { name: sonata.admin, manager_type: orm, label: 'admin.name.post', group: 'admin.group.blog'}
And the CRUD Controller:
namespace BlogBundle\Controller;
use Sonata\AdminBundle\Controller\CRUDController as Controller;
class PostAdminController extends Controller
{
public function facebookAction()
{
}
}
Looking at the profiler the route is not being generated and the button for my custom route is not displayed on the list even if it is set on the configureListFields function.
Symfony's version is 3.2.2 and Sonata 3.10.3