Came across this thread via Google and just had to create an account to try to help, I know how frustrating these rattles can be
Anyway, the rattle you have sounds like a rattle I had on my MK7 GTD - it was actually coming from the glove box.
So when you open the glove box, inside is a little plastic part on the upper right for coins and business cards, this thing (number 3 in the image):
View attachment 231043
That part moves up and down in its housing while driving, and it caused my rattle. Its pretty snug, but I managed to squeeze some soft fabric in between the orange lines so it was more firm in it's housing... and voila! That solved the rattle for me.