getGroupsStatic always says group is visitor

[GS VISION]

Hello, I have to do some limitations dependant of customer group and as it is not defined in smarty at category controller I had to include it myself so I can do my checkups. What I did was use the Customer getGroupsStatic() method which gets the groups of the user and puts them into an array

public static function getGroupsStatic($id_customer)
	{
		if (!Group::isFeatureActive())
			return array(Configuration::get('PS_CUSTOMER_GROUP'));

		if ($id_customer == 0)
			self::$_customer_groups[$id_customer] = array((int)Configuration::get('PS_UNIDENTIFIED_GROUP'));

		if (!isset(self::$_customer_groups[$id_customer]))
		{
			self::$_customer_groups[$id_customer] = array();
			$result = Db::getInstance()->executeS('
			SELECT cg.`id_group`
			FROM '._DB_PREFIX_.'customer_group cg
			WHERE cg.`id_customer` = '.(int)$id_customer);
			foreach ($result as $group)
				self::$_customer_groups[$id_customer][] = (int)$group['id_group'];
		}
		return self::$_customer_groups[$id_customer];
	}

The problem is it always gives me the customer is visitor (array has only one member which says customer group is 3). I tried the query on the database and it is correct, so something else is modifing it.