widget product reference line-item unable to be used with radio buttons in stead of select list?

I would like to let users select a product by using radio buttons. This option is available in the line-item configuration page. You can select the widget being used as radio buttons opposed to select list which is default. It works correctly with product fields being used in the add to cart form though. If you tell that a certain field on a product should be used in the add to cart form and you select the widget as being radio buttons, radio buttons is what you get.

However, every change I make is not being reflected on the node of the respective product. I always get the select list widget, never the radio buttons.

Seems like a bug or....

Can anybody help out here?