Menu not working on sub-pages

Hi there, The menu-button is working correctly on my homepage. But as soon as i navigate to one of the subpages, the menu is blank. I've tried this on my desktop (Edge, Chrome) and on my Android Phone .. all have the same behaviour. I've tried changing the template of the pages to "default template", but this didn't work. Read this somewhere in one of the threads. Everything is up2date. Hope you can help. The website is www.mixedfeelings.nl