PDO Prepared Statement: Fetch NULL instead of the expected Result

i don't get the Problem. I have in PHP a SQL Query. If i fire the query via PDO and prepared statements, but without placeholders, i get my expected result. But the product ID in the query comes from outside, so i will replace it with a placeholder :productID. If I do this, i get NULL as a result.

SQL Query:

SELECT 
COUNT(`stock`.`product`) AS COUNT,
`product`.`name_en` AS NAME,
`product`.`default_consumption` AS `DEFAULT_CONSUM`
FROM `stock`
RIGHT JOIN `product`
ON `stock`.`product` = `product`.`id`
WHERE `product` = :productId

If I replace the placeholder :productId with a valid ID in the database table (for example 1) i get my expected result.

$query = "SELECT 
          COUNT(`stock`.`product`) AS COUNT,
          `product`.`name_en` AS NAME,
          `product`.`default_consumption` AS `DEFAULT_CONSUM`
          FROM `stock`
          RIGHT JOIN `product`
          ON `stock`.`product` = `product`.`id`
          WHERE `product` = 1";
$query = $this->db->prepare($query);
$query->execute();
$response = $query->fetch(PDO::FETCH_ASSOC);
var_dump($response);

Output

array(3) {
  ["COUNT"]=>
  string(1) "0"
  ["NAME"]=>
  string(6) "butter"
  ["DEFAULT_CONSUM"]=>
  string(3) "0.1"
}

Now i will replace it:

$query = "SELECT 
          COUNT(`stock`.`product`) AS COUNT,
          `product`.`name_en` AS NAME,
          `product`.`default_consumption` AS `DEFAULT_CONSUM`
          FROM `stock`
          RIGHT JOIN `product`
          ON `stock`.`product` = `product`.`id`
          WHERE `product` = :productId";

$query = $this->db->prepare($query);
$query->execute(array(':productId' => $productId));
$response = $query->fetch(PDO::FETCH_ASSOC);
var_dump($response);

Output

array(3) {
  ["COUNT"]=>
  string(1) "0"
  ["NAME"]=>
  NULL
  ["DEFAULT_CONSUM"]=>
  NULL
}

$productId is a value from outside. In my test i set it to 1, like in my first example. I get the result NULL for the to fields DEFAULT_CONSUM and name If i set the ID 1 direct in the execute():

$query->execute(array(':productId' => 1));

I get NULL again. If i replace the :productId in the query again to the direct ID of 1, i get the espected result again. I don't get the problem at the moment.

I work with PHP 8.0 and MariaDB. The code above runs in a seperated function. There is in the moment no other code executed.

Thanks for your help. I sure, i'm overlooking something.

CREATE TABLE

CREATE TABLE`product`(
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT 'ID of the Product',
    `name_en` VARCHAR(255) NOT NULL COMMENT 'Name of the Product in Englisch',
    `name_de` VARCHAR(255) NULL COMMENT 'Name of the Product in German',
    `name_fr` VARCHAR(255) NULL COMMENT 'Name of the Product in France',
    `group` INT(10) UNSIGNED NULL DEFAULT 1 COMMENT 'ID of the Product Group',
    `unit` INT(10) UNSIGNED NOT NULL DEFAULT 1 COMMENT 'Id of the Unit',
    `default_consumption` FLOAT(10) UNSIGNED NOT NULL DEFAULT 0.5 COMMENT 'Value for Default Consumption',
    `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT 'Timestamp of creation Time',
    `changed_at` TIMESTAMP NULL ON UPDATE CURRENT_TIMESTAMP COMMENT 'Timestamp of changed',
    `deleted_at` TIMESTAMP NULL COMMENT 'Timestamp of deleted',
    PRIMARY KEY(`id`),
    INDEX `product_name_en_idx`(`name_en`),
    INDEX `product_name_de_idx`(`name_de`),
    INDEX `product_name_fr_idx`(`name_fr`),
    INDEX `product_group_idx`(`group`),
    CONSTRAINT `product_group_fk` 
        FOREIGN KEY(`group`)
        REFERENCES `product_group`(`id`)
        ON UPDATE CASCADE
        ON DELETE SET NULL, 
    CONSTRAINT `product_unit_fk` 
        FOREIGN KEY(`unit`)
        REFERENCES `unit`(`id`)
        ON UPDATE CASCADE
        ON DELETE RESTRICT
)ENGINE=InnoDB;

CREATE TABLE `stock`(
    `product` INT(10) UNSIGNED NOT NULL COMMENT 'ID of the Product',
    `user` INT(10) UNSIGNED NOT NULL COMMENT 'ID of the User',
    `stock` FLOAT(10) UNSIGNED NOT NULL DEFAULT 0 COMMENT 'Stock Value',
    `individual_consumption` FLOAT(10) UNSIGNED NULL COMMENT 'Individual Consumption Value',
    `ki_value` FLOAT(10) UNSIGNED NULL DEFAULT 0.000 COMMENT 'KI Up Down Value',
    `last_buy` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT 'Timestmap of last Buy',
    INDEX `stock_product_idx`(`product`),
    INDEX `stock_user_idx`(`user`),
    CONSTRAINT `stock_product_fk`
        FOREIGN KEY(`product`)
        REFERENCES `product`(`id`)
        ON UPDATE CASCADE
        ON DELETE RESTRICT,
    CONSTRAINT `stock_user_fk`
        FOREIGN KEY(`user`)
        REFERENCES `user`(`id`)
        ON UPDATE CASCADE
        ON DELETE RESTRICT
)ENGINE=InnoDB;