An interesting issue. I have installed the drag and drop matching question and the header when editing the question says it is a drag and drop matching question. (marked as 1. in the image). But when the question displays, it is displaying as a typical matching question with the choose box next to each item (marked as 2. in the image).
Is this because of the Rocket theme? Or perhaps because I have the Bootstrap Styling enabled? I will test, but thought you might like to know, if nothing else.