Hey, been on holiday so haven’t replied. We swapped my wind deflectors for his and it was still the same, so that ruled out the deflector itself. So it must be the fitting of it. I've had my door cards of a few times due to speaker change and had to replace wing mirror after smashing the old one to bits hitting a pigeon mid-flight.
You say you have loosened your wing mirror and it worked, but you can’t take the window down now as it might not go up again. Just an idea. But remove the wing mirror and put a spacer on the bolt between the outside of the door and the wing mirror, therefor effectively moving the mirror away from the door. Giving you a bigger gap for the deflector. I could make you a couple of thin shims to try if you like, alternatively just cut out some from cardboard and try it.