Installed last night in less than 5 minutes. This piece is also very well made. I did have to add felt pads so that it would close without catching. You can see one of the 3 at the bottom left.
But every video I have seen shows leaves, dust and crude in the filter which would not be blocked without it, unless there is something elsewhere preventing it from passing through.
This is crazy. I don't get it in any way. I'm gonna guess it is a design flaw with some randomly produced covers like batches that were accidentally installed but since this has happened over years, I really am confused.