Os X: Lock File ~/application Support/bittorrent Sync Stops Sync From Running

[sanpitch]

Hi,

 

I've been using BitTorrent Sync for about six months with no problems until now.  I've put it on 2 OS X machines, and one old Linux box.  My problem is with a late 2013 MacBook Pro that was recently updated to Yosemite.   I currently can't get Sync to run;  It somehow thinks that there is another Sync instance running,  creates a lock file in ~/Library/Application\ Support/BitTorrent\ Sync, and then exits.  So to be clear, this is not a problem with the real functionality of Sync, but with just getting Sync to run.

 

Here are steps I've taken several times just to see if I can get Sync to start

* Remove following BitTorrent Sync files and dirs
    ~/Library/Caches/com.bittorrent.Sync/

    ~/Library/Preferences/com.bittorrent.Sync.plist

    ~/Library/Application\ Support/BitTorrent\ Sync
* Move the Sync app to the trash and empty it   :-)

* Remove the Sync entry in my "Login Items"

* Reboot, reinstall the latest Sync
* Run Sync (from command line gives same result)
* Go to  ~/Library/Application\ Support/BitTorrent\ Sync and see a new 'lock' file.
* Rinse repeat, just in case I was doing something stupid

I guess that somehow Sync thinks it's still running when I start it again, but I just can't figure out how.   I recently updated to Yosemite, which may have triggered this problem, but others are working fine with Yosemite.   I tried botht the default build from the BT website and the dmg from http://syncapp.bittorrent.com/1.4.103/  I also tried as a different user, with the same result.   I have also contacted BT support at  syncapp@bittorrent.com; they responded once but have not responded in six days.
 

Any ideas? Hopefully there is a quick fix.