If I make a screen that's full of 'snowing' tiles, and nothing else, and set it to layer '6' on a screen, then all secret combos on that screen don't function properly...
Like, it makes a black square. I know what it's doing, though. Because layer 6 appears over everything else, it layers a blank tile over the secret combo.
I've run into this problem time and time again, but this time it's a little different. Even with that, it shouldn't do that because the only layer used is a snow screen, which contains transparent tiles. Do they become 'apparent' when you trigger a secret combo over the one that was triggered?