Hide out of stock products from related products

Hey,

I have read all articles about this problem. But none of the snippets work.

I have testet:

add_filter( 'woocommerce_output_related_products_args', function( $args )
{
    $args = wp_parse_args( array(
        'posts_per_page' => 4,
        'meta_query' => array (
           'key' => '_stock_status',
           'value' => 'instock'
    )
    ), $args );
    return $args;
});

But it didnt work.

Any ideas how to hide the out of stock products ONLY from the related products?

Thanks!
Robb