Dynamic sidebar areas not working on the Theme Customizer

Creating new query objects is not a good idea in this situation. Try simply getting the pages and using those objects to serve up the widget areas:

add_action( 'widgets_init', 'my_243057_widgets_init' );

function my_243057_widgets_init() {

    /**
     * Get only published page objects
     * @link: https://codex.wordpress.org/Function_Reference/get_pages
     */
    $pages = get_pages();

    foreach ( $pages as $page ) {

        register_sidebar( array(
            'name'          =>  'Widget name',
            'id'            => 'widget-id-' . $page->ID,
            'description'   => __( 'Widget for page: ' . $page->post_title ),
            'before_widget' => '<div>',
            'after_widget'  => '</div>',
            'before_title'  => '',
            'after_title'   => '',
        ) );
    }
}