Symfony Doctrine not working when uses "SEQUENCE" as GeneratedValue in Oracle-CodePudding

I have the following Entity in Symfony 2 with an ID generated by an Oracle Sequence:

namespace PSBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Table(name="CONTRATO")
 * @ORM\Entity
 * @ORM\Entity(repositoryClass="PSBundle\Entity\ContratoRepository")
 */
class Contrato
{
    /**
     * @var integer
     *
     * @ORM\Column(name="ID_CONTRATO", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="SEQUENCE")
     * @ORM\SequenceGenerator(sequenceName="SID_CONTRATO", allocationSize=1, initialValue=1)
     */
    private $idContrato;

    // Other fields...
}

But when I do:

$entityContrato = new Contrato();
// Set some fields
$em->persist($entityContrato);

I get:

Entity of type PSBundle\Entity\Contrato is missing an assigned ID for field 'idContrato'. The identifier generation strategy for this entity requires the ID field to be populated before EntityManager#persist() is called. If you want automatically generated identifiers instead you need to adjust the metadata mapping accordingly.

I know that SID_CONTRATO is well defined as if I select the NEXTVAL it works:

What I'm missing? Any kind of light in the subject would be more than appreciated, my related dependencies are:

"php": "7.2",
"symfony/symfony": "2.3.42",
"doctrine/orm": "2.3.x-dev",
"doctrine/doctrine-bundle": "1.2.0",

Doctrine config (from config/config.yml, I don't have a doctrine.yaml file):

# Doctrine Configuration
doctrine:
    dbal:
        driver:   oci8
        port:     1521
        dbname:   ORCL
        host: