There was something in the logs about a "file too long" error. After I have renamed the file with a shorter name, sync resumed. Now It seems to work when I add new files. It may be a coincidence, i'll check if this problem happens again. Btw i've seen in the logs that btsync sends a "rename" command instead of redownloading the entire file. That's awesome. Does it detects if I move the file in a subdirectory ?