I have been running BitTorrent Sync 1.3.94 on a Synology 412+, installed via the SynoCommunity package, for some months without difficulty. With the synology as the central file repository, I've successfully kept files in sync between an always-on MacMini that runs Apple Mail and Hazel rules; and a MacBook Pro laptop, an iPhone, and an iPad. Everything has worked flawlessly until recently, and I can't figure out what has gone wrong. Suddenly I found I was having sync issues with a few of my more-used folders. I deleted them from sync and tried to re-add the folders thru the Synology BTS interface, only to receive the dreaded "you don't have permissions to write to the selected folder" error. I have checked and re-checked permissions on the folders in question, but I can't see any differences between how they're configured, and other folders that i've added in BTS on the synology and which work fine. I've tried adding test folders via the Shared Folder or File Station interfaces; doesn't seem to matter, still get the above error when I try to add them to BTS. Doesn't matter whether I access the Synology from my MacBook Pro or from the Mini; same error. I'm logging into the Synology over my LAN via a user account that has administrative privileges. This has to be a permissions issue of some sort, but for the life of me I can't figure out what changed, or where the problem lies. I've had to go back to Synology Cloud Station sync in the interim, but that is slow as Christmas. Any ideas would be welcomed as manna.