Not picking up new files in Dropbox Camera Uploads folder

I'm using Hazel v3.1.5 (build 1038) with Dropbox v2.0.26 on Mac OSX Mountain Lion 10.8.5
I have 1 folder added to Hazel that is supposed to be watching my dropbox "Camera Uploads" folder (I'm using the "Camera Upload" feature on the dropbox iPhone app).
If I preview the rules, or run the rules manually then Hazel will pick up new files that dropbox has put into the camera uploads folder. However, hazel will not pick up the files automatically
I have tried copy/pasting files myself using Finder into the Dropbox Camera Uploads folder and get the same result (hazel doesn't "see" them as new files).
I have 1 folder added to Hazel that is supposed to be watching my dropbox "Camera Uploads" folder (I'm using the "Camera Upload" feature on the dropbox iPhone app).
If I preview the rules, or run the rules manually then Hazel will pick up new files that dropbox has put into the camera uploads folder. However, hazel will not pick up the files automatically

I have tried copy/pasting files myself using Finder into the Dropbox Camera Uploads folder and get the same result (hazel doesn't "see" them as new files).