I'm running Dropbox basic on three devices, including a Windows 10 laptop and a Windows 7 PC. The PC mysteriously stopped downloading files, so I tried to diagnose it. I repeatedly uninstalled/reinstalled Dropbox, deleted the folders, rebooted the computer etc. Yes, I've got terabytes of free space on the PC. No, I'm not using selective sync.
I even tried deleting the files off the cloud and re-uploading them. When I started doing that, I saw something interesting. As I uploaded each file to the cloud, I would see my laptop download the file, just like it is supposed to. But on the PC, it would create the final destination folder, but only download the file to the .dropbox.cache folder and just leave it there, file after file. So the PC ends up with the full directory structure, but for some reason the only files that get moved there are those that are 1KB -- everything larger just stays put in the cache folder.
OK, that sounded like a great theory, since I do have a blocker app on the PC that isn't on the laptop -- obviously everything worked fine before and I haven't changed any hardware, software, or settings, so it should still be working fine, but you never know for sure what programs do on their own, so I decided to test it. I cleared the blocker's log and kept an eye on the (now blank) log while I repeated the whole process I did before of deleting a whole directory of stuff on Dropbox and re-uploading it -- but nothing showed up in the log, and once again, the files got downloaded to the cache and just stayed there.
Re: Dropbox not moving downloads from .dropbox.cache to final directory