found out (after disabling all my plugins and activating them one-by-one), it’s a combination of 3 plugins:
– WP Page Widget
– Bol.com partner plugin by Netvlies (https://wordpress.org/plugins/bolcom-partnerprogramma-wordpress-plugin/)
– Yoast
When this combination is active, it brakes. Disabling bol.com or yoast resolves the problem.
I can confirm that the problem with Yoast is there. Also with standard theme activated.
