Well it looks like I'm the idiot here. :(

I just did another as_string since you're right it REALLY shouldn't be empty.

It did in fact contain the headers and then this X-Died: Can't locate HTML/HeadParser.pm in @INC

Looks like that's the problem. I _swear_ on my sanity (yikes) that as_string returned blank yesterday. Maybe I'm dilusional...

Thanks, and sorry for wasting your time!

EDIT: Well at least I'm not a total idiot ;) I did in fact have the HeadParser module installed, but apparently it was broken because I just reinstalled it and everything works as expected. I hate computers...