Toggle Mobile Menu Not Working

Hello Community,

The toggle mobile menu is not working. It’s there, I can see it, but so long I tap on it from the phone, nothing happens. The categories (the pages) don’t collapse, it’s not shown. When I reduce the screen size of my desktop (on computer) to test it, it works (the pages will be collapsed), but on the mobile phone, it’s not. Can somebody give me a good insight? Through some posts researchs here, I’ve tried some tipps like to load the original header.php file into the child theme, changing the float of the primary navi menu etc, but without any success. My site is https://ncm-pm.de/.

Thanks & Regards,

medde