Add filter to acf relationship field

I am using wordpress 4.9.7 and I am using advanced custom fields 4.4.12.

In my backend I have a post type that is called coins, which has a relationship field called related_coins and a text-field, which is called algorithm. Basically my relationship field creates a relationship to the custom post type products. So product can have a relationship with several coins.

I currently only can filter by post type. However, I would like to filter by the custom field algorithm of the post type coin.

I tried the following:

function graphic_card_products_query( $args, $field, $post_id ) {

    $args['meta_query'] = array(
        array(
        'key' => 'algorithm', // name of custom field
        'value' => 'related_coins',
        'compare' => 'LIKE'
        )
    )

    // return
    return $args;

}

// filter for every field
add_filter('acf/fields/relationship/query/name=related_coins', 'graphic_card_products_query', 10, 3);

Basically I am trying to get a list of all values that the custom field algorithm has and hand it as a filter option back to the relationship field related_coin.

Currently I do not get anything back.

Any suggestions what I am doing wrong?

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