Until recently, I too had a never-ending sync of just 52.5 KB pending (plus a file count difference of 1). Removing and re-adding folders didn't help, so I investigated. After checking each folder's file count one-by-one, I found the culprit! At some point, I had renamed a folder on my Windows machine, changing only the case of some letter (let's say from 'contest_winners.xls' to 'Contest_Winners.xls'). However, I found two identical files on my Linux NAS: 'contest_winners.xls' and 'Contest_Winners.xls' side-by-side. It seems that the difference in case-sensitivity from Windows to Linux threw off the indexing engine, and it created the duplicate. So, the 'contest_winners.xls' file tried to sync back to the Windows machine (after some changes) and found no counterpart, staying in limbo I guess. Whether this is an issue to be fixed, or a one-case scenario, I don't know. I'm just putting it out here.