WebService Prestashop : unable to update attributes product quantities

[t-prod]

Hi,

I'm using the Prestashop WebService 1.7.4.2 and I try to update attributes products quantities but it doesn't work at all :

I have a product and 5 combinations and the stock_availables endpoint only list product parent but not the attributes

I try to update like this :

$combination = Prestashop::get(
    [
        'resource' => 'combinations',
        'id' => (int) $product_combination->id
    ]);
$putXmlCombination = Prestashop::fillSchema($combination, ['quantity' => 5], false);
Prestashop::edit(
[
    'resource' => 'combinations',
    'putXml' => $putXmlCombination->asXml(),
    'id' => (int) $product_combination->id
]);

But combination quantity is not updated at all in BO despite the fact the return is good :

In BO : It should be 5 but it's 4

Regards