[BUG] Product attribute save, is_taxonomy = 1

Hello,

I’m trying to save product_attributes (attribute ‘pa_raretes’ and value ‘RR’ exist) :

$product_attributes['pa_raretes'] = array (
                        'name' => 'pa_raretes',
                        'value' => 'RR',
                        'position' => 0,
                        'is_visible' => 1,
                        'is_variation' => 0,
                        'is_taxonomy' => 1
                    );
update_post_meta($id, '_product_attributes', $product_attributes);

The problem is that the value is not saved, only the attribute as taxnonmy with empty value.. When I set is_taxonomy => 0 I have to update manually the product to make it works. I don’t understand …