Sometimes user meta are not saved

Hello,

I have a problem with MB User meta.
Sometimes, the meta just does not save.

Look the screencast : https://screencast-o-matic.com/watch/cbQIXiI2S0

My code is below,

<?php

add_action( 'rwmb_meta_boxes', 'vm_user_meta_boxes' );
function vm_user_meta_boxes( $meta_boxes )
{
    $meta_boxes[] = array(
        'title'      => __( 'Options', 'vm' ),
        'type' => 'user',
        'fields' => array(
            array(
                'name'    => __( 'Structure culturelle', 'vm' ),
                'id'      => 'vm_cultural_structure',
                'type'    => 'post',
                'post_type'    => 'cultural_structure',
                'desc'    => 'Structure culturelle associée à l\'utilisateur',
                'query_args' => array(
                    'post_status' => 'all',
                ),
            ),
        ),
    );

    return $meta_boxes;
}

Do you have an idea ?