menu does not show on mobile

Can you help me please? Menu (hamburger menu) does not show on mobile. It happens when I activate child theme. But before it worked without problems all these years (same child theme)
(parent theme is SIMPLIFY).

someone from SIMPLIFY support first said “that some files are not loading properly on my site. Please re-install the Theme SIMPLIFY and Clear the Cache of your site. ”

So I did reinstall the theme + installed a caching plugin following their advice. But when I activate my Child theme again, same story, menu’ does not show anymore on mobile. I simply cannot work like that. Any idea?

P.S. for reference: my simplify_child folder has 2 files:

functions.php

<?php
/**
* Enqueues child theme stylesheet, loading first the parent theme stylesheet.
*/
function simplify_custom_enqueue_child_theme_styles() {
wp_enqueue_style( ‘parent-theme-css’, get_template_directory_uri() . ‘/style.css’ );
}
add_action( ‘wp_enqueue_scripts’, ‘simplify_custom_enqueue_child_theme_styles’, 11 );

/* Remove category from category widget */
function dtwd_exclude_widget_category($args){
$exclude = “7”; // IDs of excluding categories
$args[“exclude”] = $exclude;
return $args;
}
add_filter(“widget_categories_args”,”dtwd_exclude_widget_category”);

style.css
(no code)

Thank you so much for any hints

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