Not sure if it's a bug or if I'm not understanding that option, but there are 3 choices: main, main+subfolders, and specific subfolder.
Isn't this meant to be setup for quick dress? As if, if I create a "wear" subfolder inside the main, select the last option with that folder, when I quick wear it'll only attach what's in "wear"? Because it doesn't do that for me, it still wears stuff in the main folder.