I'd lay money on the answer being a bug somewhere -- we don't have many people using the API (because it's so old and out of date), so things like backwards compatability issues with newer versions of Perl or Perl modules we use don't tend to get caught very quickly -- but try making a top-level dw-dev post and see if anybody has any suggestions?

(We know the API is in a dreadful state; we've been working on a replacement that was actually architected in this century...)