@andres-garcia Sorry for the late response, kinda slammed.
https://fusionauth.io/docs/v1/tech/samlv2/#limitations says
FusionAuth supports only the following NameIDPolicy values:
urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress urn:oasis:names:tc:SAML:2.0:nameid-format:persistent urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified
So it seems like that isn't supported. Please feel free to file an issue https://github.com/fusionauth/fusionauth-issues/issues referencing this forum post and explaining you'd like this new NameIDPolicy value to be supported.
If you are a customer with a support contract, it's helpful if you file a support ticket as well. This helps us prioritize future work.