Issues with Dropbox and Collect Files

I ran into an issue today while trying to collect files for a large project to archive it. I have a single graphics project for a web series which needs to be broken out by episode. Most of the assets for my project are stored on a local hard drive, but one or two files over the last few months have been living in a Dropbox folder that syncs to my computer.

PROBLEM:

I had no issues reducing and collecting the files for the first handful of episodes, but then when I got a few projects in, the "Collect Files" button stopped working. The project would save if I had made any changes, but no window would pop up. Nothing.

SOLUTION:

After digging around in the project I found that one file for this episode was in a Dropbox folder, but was not synced locally (it was "online only"). Syncing it to my hard drive immediately solved the problem and the "Collect Files" window popped up again, like normal.

Hope this helps anyone else that runs into the same issue!