As the replacement was rendered, the file in the host’s Dropbox folder seemed fine, but the rest of us were caught in an infinite sync cycle in which nothing was actually being downloaded.
This problem was caused by a conflict in Dropbox’s cache.
To check this, right-click on the Dropbox icon in your task bar and select Preferences.
Once there, head over to Advanced and select Selective Sync…. One trick to resolve sync errors I found is renaming the problematic folder through the Dropbox website.
If you’re still experiencing issues, you may want to investigate further to see if the ports Dropbox is using are in conflict with other applications and/or systems on your network.