We haven't had a post on this topic for quite a while.Is this a common problem?
This power window feature is called the Short-stroke in the WIS, and the details are shown below for, your interest. It can be noted that one of the pre-requisites for the operation is that the window is normalized. As with many aspects of this car, MB have 'engineered the sh1t' out of the feature, as my old boss would say.
The reasons for short-stroke are not too clear. I always imagined that it was to prevent a high air pressure situation when the doors are closed quickly - but that would not be a problem on the cabriolet, would it?
I do know (from experience) that if the side windows are covered in frost/ice, they can be stuck in position and this short-stroke movement will be prevented. In those situations, I always use a de-icing spray to remove all the ice on the window glass before using my remote key to open the door.