I ran into this as well. Had a shared folder syncing between two machines A and B, and had the exact same contents on a third machine C (OS X). Entered the key on C and chose the existing folder, it is connected, says that it tries to sync but nothing is happening (0 B/s transfer). Because I have 20 GB in there, synchronizing to an empty folder seems ridiculous since the machine already has the files. Please advise.