So my 2015 Q60s vert has an annoying rattle, behind the drivers seat when the top is down. It appears on uneven road surfaces at slow speeds. It sounds like two metal pieces coming together when the road is buckled.

I checked the trunk area and everything is rock solid. I tightened most bolts and nothing seemed out of place. I thought it could be some of the convertible arms hitting each other, but I can’t move them

any tips or tricks of the cause? Thx!