Design Type “Theme Default” not working

Hi there,
I’m a very happy customer of your plugin!
But since the last update of your plugin, there is a little issue …
I use the the design type “Theme Default” for showing dropdowns for a global attribute.
Since the last update, for this design type the add-to-cart function isn’t working any more (does nothing)!
As a workaround I have changed the design type to “Dropdown” for this global attribute, which works still correctly.
Can you please help me with this?
Thanks.