Salutation is not working in Newsletter Form even Salutation elements exists

Hello there. I setup a Newsletter subscription form inside my landing page. I used the standard Newsletter form. Everything works fine except the Salutation field displays a blank list of options despite the Salutation list has been already setup. I attach both screens.

I have no problems with the Salutation field when the customer is making his order (see third screenshot)

Any help is very valuable! thanks.