Add to Cart in wooCommerce just relode page and the cart is still empty

When I click on “add to cart” in the product page nothing happens. It just reloads the page but no item is added to the cart.

When I′m logged in as administrator it works fine.
The cart also works if I click on “Add to cart” in the product listing overview.
if i do the paypal-checkout it also works.

I installed some plugins
– avada theme
– german market plugin
– facebook for woocommerce
– paypal checkout
– stripe gateway

I tried to
– disabled all plugins
– tried another theme
– disabled nginx-cache
– cleard / deactivated cache
– tried different browsers
– tried on mobile devices
– deactivated Ajax in woocommerce product settings

The page I need help with: [log in to see the link]