Custom portfolio taxonomies not visible in second language Portfolio grid

Hi,
For the post type Portfolio I registered 3 additional Taxonomies to choose from.
This works perfect in the standard language (Dutch): https://www.iqheadquarter.nl/uniiq/portfolio/
But on the English version I cannot choose the additional categories in the Portfolio grid: https://www.iqheadquarter.nl/uniiq/en/portfolio/
They are missing from the ‘Which categories should be used for the portfolio?’ field. In the not translated page it is working…

I am using WPML and Child theme in a Multisite installation.
I registered the taxonomies in functions.php of Child theme:

add_action('init', 'plaatsen_register_taxonomy');
function plaatsen_register_taxonomy() {
    $args = array( 
        'hierarchical' => true,
        'label' => __( 'Portfolio plaatsen' ),
    );
    register_taxonomy( 'plaatsen_taxonomy', array( 'portfolio' ), $args );
}

I translated the taxonomies in WPML Translation Taxonomies. I also see the taxonomies in the backend menu of both the Dutch and English website, just not in the second language Portfolio grid.

What is going wrong?

Thanks in advance,
Ariane