Why aren't any of my Folder Actions triggering?
Folder Actions seem to have been buggy for a lot of people in Mountain Lion (myself included). There’s discussion elsewhere on Ask Different about the unreliability of Folder Actions in general, and there are quite a few threads on Apple’s support forums about the issue.

Reinstalling 10.8.4 seemed to fix the problem for the OP, but I’ll note here what seems to be a common fix. The following practice, quoted from Jehan Alvani’s blog, has been cited in quite a few places:


  
  Create ~/Library/Scripts/Folder Action Scripts/ and drop the folder action script you want to add in there.
  Strangely, open System Preferences → Keyboard → Keyboard Shortcuts, and click the Reset to Defaults button.
  Scroll up to the Files &amp; Folders section, and make sure that the Folder Actions Setup… listing is checked.
  


I think you want to go to the Services panel within the Keyboard preferences pane, but I’m not certain. I’m not willing to try it since I don’t want to reconfigure my keyboard shortcuts if I screw it up, and I don’t use Folder Actions anyway.

I know the OP’s problem has been fixed, but this may be of use to other people facing similar difficulties.