Hi kranta1
The problem relates to the configuration, the content in the filter (articles) are not assigned to any menu item so that when you click to open it will not redirect to any page but homepage. I just tried to create a new menu item - a sub-menu item of 'Zoek kunstenaar' >> click the item should work now.
But the content is not showing due to the template you're using, if you use Protostar, it will show fine. Kindly check the layout of template you're using.
Regards