Preview from block list doesn't work ?

Hi,

I use MB Blocks since 2 years now but I never take the time to check the "preview" on the sidebar of Gutenberg because my clients don't want to view something.

But today, one of them ask to me to have previews on their own blocks but I don't understand how it's working (maybe it doesn't work ?)

Sample code

add_filter('rwmb_meta_boxes', function ($meta_boxes) {

    $meta_boxes[] = [
        'title' => 'Hello World',
        'id' => 'hello-world',
        'description' => 'This is a hello world block',
        'type' => 'block',
        'preview' => [
            'title' => 'My Hello World',
        ],
        'fields' => [
            [
                'name' => 'Title',
                'id' => 'title',
                'type' => 'text',
            ]
        ],
        'render_callback' => function ($attributes, $content, $block, $is_preview) {
            echo $attributes['title'];
        },
    ];

    return $meta_boxes;
});

The result on Gutenberg on my side

PHP: 8.2
Wordpress version: 6.7.1
Meta-Box: 5.10.6
Meta-Box-Aio: 1.31.1