permastruct for custom post type not working in one of four cases

I've created custom permalinks for various custom post types on a website. They all worked. Until recently I added another one, which I cannot get to work 8-o. The "company" struct is not working and gives a 404..

Can anyone spot a flaw in my thinking or put me on the right track? I must be forgetting something very stupid ;-)

Oh, I also went to the permalink settings page to flush the old permalinks / permalink cache / ...

Here's the code for the custom structure:

// rewrite rewrite
global $wp_rewrite;

$wp_rewrite->add_rewrite_tag("%merkname%", '([^/]+)', "merk=");
$wp_rewrite->add_permastruct('merk', '/merken/%merkname%', false);

$wp_rewrite->add_rewrite_tag("%modelname%", '([^/]+)', "model=");
$wp_rewrite->add_permastruct('model', '/merken/%merkname%/%modelname%', false);

$wp_rewrite->add_rewrite_tag("%carname%", '([^/]+)', "car=");
$wp_rewrite->add_permastruct('car', '/merken/%merkname%/%modelname%/%carname%', false);

$wp_rewrite->add_rewrite_tag("%companyname%", '([^/]+)', "company=");
$wp_rewrite->add_permastruct('company', '/company/%companyname%', false);

function kw_custom_permalink($permalink, $post, $leavename) {

    if ( '' != $permalink && !in_array($post->post_status, array('draft', 'pending', 'auto-draft')) ) {

        $merkname='';
        $modelname='';
        $carname='';
        $companyname='';

        if ( strpos($permalink, '%merkname%') !== false ) {
            $merkname = $post->post_name;
        }

        if ( strpos($permalink, '%modelname%') !== false ) {
            $merkpost = get_post( get_post_meta( $post->ID, "merk", true ) );
            $merkname = $merkpost->post_name;
            $modelname = $post->post_name;
        }

        if ( strpos($permalink, '%carname%') !== false ) {
            $merkpost = get_post( get_post_meta( $post->ID, "_car_merk", true ) );
            $merkname = $merkpost->post_name;

            $modelpost = get_post( get_post_meta( $post->ID, "_car_model", true ) );
            $modelname = $modelpost->post_name;

            $carname = $post->post_name;
        }

        if ( strpos($permalink, '%companyname%') !== false ) {
            $companyname = $post->post_name;
        }

        $permalink = str_replace(
            array(
                $leavename? '' : '%postname%',
                '%post_id%',
                '%merkname%',
                '%modelname%',
                '%carname%',
                '%companyname%',
                $leavename? '' : '%pagename%',
            ), 
            array(
                $post->post_name,
                $post->ID,
                $merkname,
                $modelname,
                $carname,
                $companyname,
                $post->post_name,
            ), 
            $permalink
            );

    }
    return $permalink;
}
add_filter('post_type_link', 'kw_custom_permalink', 10, 3);