Re: Vectors not autocompleting?
The version was set to Air 3.1; setting it to Air 3.2 didn't help, nor did Flash Player 11.3.
Anyway, I finally decided to try what I guess I should have done in the first place -- I completely uninstalled FD, and reinstalled it, and now it works fine.
I guess we'll never know what went wrong, but as long as it's that easy to fix I guess it doesn't matter anyway.
Thank you for your help though!
(Interesting side note: now that I've reinstalled, it even works for my older projects, so it definitely wasn't a project configuration issue.)