It turns out it DOES eventually find "art" if I just leave it running long enough, so I was going off half-cocked.
What threw me was that it is taking so much longer than my non-module lisp-like version. It's taking 7,758 perms to get to 'art' (same number twice).
But the module-free version started with 'a' and worked its way through alpabetically, thus getting to art very quickly. Without thinking, I was expecting Permute to get there even faster, but the man page says there's no guarantee about the order that the module produces perms.
So I guess it's working as expected.
My apologies, my bad.. Thanks for the responses.