mb_blocks_preview event not firing

I have made a custom slider block, unfortunately it does not execute in gutenberg for preview.

$meta_boxes[] = [
            'title'           => 'Slider',
            'id'              => 'slider',
            'description'     => 'Flexibler Slider',
            'type'            => 'block',
            'icon'            => 'images-alt',
            'category'        => 'common',
            //'context'         => 'side',
            'render_template' => get_template_directory() . '/blocks/slider/template.php',
            'enqueue_style'   => get_template_directory_uri() . '/blocks/slider/style.css',
            'enqueue_script'   => get_template_directory_uri() . '/blocks/slider/slick.min.js',
            'supports' => [
                //'align' => ['wide', 'full'],
                'customClassName' => true,
                'anchor'          => true,
            ],

        // Block fields.
        'fields' => [
            [
                'id' => 'slider_group',
                'type' => 'group',
                'name' => 'Slides',
                'default_state' => 'expanded',
                'clone'  => true,
                // Drag and drop clones to reorder them?
                'sort_clone' => true,
                'fields' =>
                    [
                        array (
                            'id' => 'slide_image',
                            'type' => 'single_image',
                            'name' => 'Hintergrundbild',
                            'required' => true,
                        ),
                        array (
                            'id' => 'slide_text',
                            'type' => 'wysiwyg',
                            'name' => 'Text',
                            'raw' => true,
                            'required' => false,
                            'options' => array(
                                'textarea_rows' => 4,
                                'media_buttons' => false,
                                'wpautop' => false,
                                'teeny'         => false,
                            ),
                        ),
                    ]
            ]
        ],
    ];

( function( $ ) {
    function initSlider() {
        console.log("initSlider!");
        $('.slider').slick({
            lazyLoad: 'ondemand',
            dots: true,
            infinite: true,
            speed: 500,
            fade: true,
            cssEase: 'linear',
            slidesToScroll: 1,
            autoplay: true,
            autoplaySpeed: 9000,
        });
    }
    // Run when a document ready on the front end.
    $( document ).ready( initSlider );
    // Run when a block preview is done loading.
    $( document ).on( 'mb_blocks_preview/slider', initSlider );
} )( jQuery );

Is there more information about the mb_blocks_preview event?

Script is executed fine in frontend.