I solved this. It was actually quite simple. When the new front page with additional regions was built, the actual page content was excluded from the tpl.php file. So the the old front page view was also the new front page, it just wasn't displayed. So when I edited the path of the views page, the front page path didn't exist anymore and the menus weren't displayed on that page. I can explain it better if anyone would be interested.
Thanks for pushing me to have a second, deeper look into the database.