Case insensitiveness is so wrong. Especially if it's mixed with case sensitiveness within the same application. And apparently btsync uses both approaches. If it tries to access files it uses whatever the OS thinks is right but then internally it uses case sensitive comparison. For example when you rename the .SyncArchive folder to .SYNCARCHIVE on a windows machine. Then trashed files still land in this folder. But at the same time the folder gets synced to other clients because the name is no longer on the ignore list. Someone I have a bittorrent sync share with did this. And whenever I tried to delete this folder his client moved his copy of the .SYNCARCHIVE folder into the .SYNCARCHIVE folder itself and synced it back to me. So now I had a .SYNCARCHIVE/.SYNCARCHIVE folder.