The same for me. When only the 4 upper cheeses remains (and no more mousetrap), the crowns kill bottom tiles and this serves of nothing. I emailed them and they just told me (in a standard reply) that I needed to look at the tips. Still can't drop the top cheese.
Same thing here. I thought maybe there was a trick, but I have a friend who got right through a while back. None of the top cheeses drop no matter what I try. :(