My issue (read above) was solved, so if you happen to come across the same thing, here's an explanation and a workaround from Dom:
"It seems the problem comes from how Haxe, the language behind Stencyl, returns values from the list. It seems to return everything as text; when you compare this to a number, in your case 0, it also casts the string to a number, by default 0. This makes it always return true. To solve this, simply wrap the 0 in an "as text" block."
Cheers!