Add to wishlist not working

Only working when the customer is still logged in.
Without after click “your product was added” but there is nothing in the wishlist. I tried to get this working by deactivation other plugins but no success.

The shop is working with https, but only in checkout and customer-account. In my testing area without any https it’s working fine. Is this an SSL-issue?

Hopefully there will be a fix for this – I would love to use this plugin.

https://wordpress.org/plugins/yith-woocommerce-wishlist/