Symfony 4 save button to submit request keep reloading the current page - symfony

Question

Actually there's no request sent as if the function isnt even executed
it already shows in the logs that it uses POST/SponsorNew and doesn't load "SponsorListPage"
after submitting save it in the database
besides i applied the same code on another entity from the same project and it worked
//Add method
/**
* #Route("/sponsorNew",name="newSponsorPage")
*/
public function newSponsor(Request $req):Response{
//1.Create form view
$sponsor= new Sponsor();
//1.b prepare the form
$form= $this->createForm(SponsorType::class, $sponsor);
//2. Handel http request sent by the user
$form=$form->handleRequest($req);
//2.b check the form
if($form->isSubmitted() && $form->isValid()){
//3.Persist data
$em=$this->getDoctrine()->getManager();
$em->persist($sponsor);
$em->flush();
return $this->redirectToRoute("SponsorListPage");
}
//1.c render the form
return $this->render('sponsor/new.html.twig',[
'f'=>$form->createView()
]);
}
and here is the Form
class SponsorType extends AbstractType
{
/**
* #param FormBuilderInterface $builder
* #param array $options
*/
public function buildForm(FormBuilderInterface $builder, array $options): void
{
$builder
->add('nom')
->add('email')
->add('numContact')
->add('type')
->add('sponsor_save', SubmitType::class)
;
}
public function configureOptions(OptionsResolver $resolver): void
{
$resolver->setDefaults([
'data_class' => Sponsor::class,
]);
}
}
here is the template to fill the blanks
<div class="container">
<h1>Add new Sponsor</h1>
{{ form_start(f) }}
<div class="form-group">
<label>
Name of the Sponsor
</label>
{{ form_widget(f.nom,{'attr':{'class':'form-control'}}) }}
</div>
<div class="form-group">
<label>
Email of Sponsor
</label>
{{ form_widget(f.email,{'attr':{'class':'form-control'}}) }}
</div>
<div class="form-group">
<label>
Contact Number
</label>
{{ form_widget(f.numContact,{'attr':{'class':'form-control'}}) }}
</div>
<div class="form-group">
<label>
Type
</label>
{{ form_widget(f.type,{'attr':{'class':'form-control'}}) }}
</div>
{{ form_widget(f.sponsor_save,{'attr':{'class':'btn btn-sm btn-success'}}) }}
{{ form_end(f) }}
</div>