It doesn't close that much - stops about two thirds of the way
It looks like there are plastic clips, one on each side, that push the spoiler down when you wind the roof forward. From what I can tell, they're hitting the edge of the bracket that holds the arms in place, then when you wind it forward the back end of the sunroof pops up because it's sprung.
I've tried adjusting the roof so it sits higher, but it's still not clearing the clips and I'm wary that I'll wind it up just that little bit more and it'll catch and ruin the paint when I wind it back.
TBH part of me is tempted to just leave it be for now, it fits properly and I don't really use it anyway. It winds both ways without any problems at the moment, but just doesn't have a spoiler.