Quick View do not work when using WPML multilingual WordPress plugin

Because this problem cost me 2 days of research I want to leave a short note about it.

Symptoms:
– visitors of the site are not logged in
– browser is IE or Safari
– after click on the “Quick View” – button the screen overlay comes, but no popup-window is shown, the screen remains empty.
– the problem comes when the language is selected via url-parameter (e.g.: http://mypage.com/lang=de)

Solution:
enable the “language cookie” in WPML:
https://wpml.org/documentation/getting-started-guide/language-setup/enabling-language-cookie-to-support-ajax-filtering/