Image in Content Slider: Link To: 'None' does not work

Hi

On this page you can see a Content Slider: http://www.b-ild.com/
In the ‘Image Details’ in the Content Slider, you can choose for Link To: ‘None’.

Unfortunately that does not seem to work: after publishing the page, the image setting is back to Media File.

Any idea? For this website the image link should be disabled for all images in the Content Slider.

Regards

Tom