Filter "rwmb_{$field_type}_value" doesn't work

Hello,

This filter is exactly what I need to manipulate the values of my registered fields before they've been saved to the DB. but apparently, it doesn't work, including all of its variations.
I've created a test environment with only the MetaBox plugin activated, put a breakpoint inside the filter, and also print something, but it doesn't go there.

here's my code:

add_filter( 'rwmb_meta_boxes', 'test_register_metabox' ); // register fields

add_filter( 'rwmb_text_value', 'test_save_field', 10, 5 ); // test a text field by field type
add_filter( 'rwmb_group_value', 'test_save_field', 10, 5 ); // test a group field by field type
add_filter( 'rwmb_test_simple_value', 'test_save_field', 10, 5 ); // test a text field by its id
add_filter( 'rwmb_test_group_value', 'test_save_field', 10, 5 ); // test a group field by its id

function test_save_field( $new, $field, $old, $object_id ) {
    var_dump($new);
    return $new;
}

function test_register_metabox( $meta_boxes ) {
    $meta_boxes[] = array(
        'id' => 'test',
        'title' => 'Test Meta Box',
        'post_types' => 'post',
        'fields' => array(
            array(
                'id' => 'test_simple',
                'name' => 'Test Simple Field',
                'type' => 'text',
            ),
            array(
                'id'            => 'test_group',
                'type'          => 'group',
                'name'          => 'Group Test',
                'clone'         => true,
                'sort_clone'    => true,
                'fields' => array(
                    array(
                        'id'        => 'test_1',
                        'type'      => 'text',
                        'name'      => 'Text Field',
                    ),
                    array(
                        'id' => 'test_2',
                        'type' => 'wysiwyg',
                        'name' => 'HTML Field',
                    )
                )
            )
        ),
    );

    return $meta_boxes;
}

Am I doing something wrong?
I've also tried to search the filter inside the source code but didn't find anything. Is the filter even there?

Thanks!