I am in this situation now. I have Dropbox business with 3 Tb and I have lots of files... It was fine until last week or so when I tried syncing and it syncs infinite. It starts at about 7K files and I let it run. I noticed that it will be at say 7232 files then it will jump to 7258 then start decreasing. It does this constantly but file numbers will vary. Eventually it gets to about 400 or so and it says a minute left, then it jumps back up to 800 and the process repeats over and over...
Looking at the sync and storage in the app. It shows that I have like 5% of the dropbox on harddrive. This is not the case. I have it all on the drive so there is something rotten here.
I've wasted way too much time on this and nothing works. I'll probably stop using this and go with a RAID system internally and swap out drives and periodically store one off site.