Apparently I sync'd from the wrong direction (machine) and my old MBP now has only one default container now. The dozen or so containers I had have disappeared. You need to be clearer in your directions and define the use cases. In my case I want to port over FF from an old MAC to a new MAC. This would include my settings, configuration history, folders, bookmarks, extensions, homepage, and my containers to a new MBP - so it looked like the old one. Eek I thought it would be smarter and see that the new MBP was a newer version and had no configuration. Now I have blown away the containers and have to remake them. I also notice now that my settings - home page, history are not the same yet so I will have to look into what is going on there. I am disappointed with the way this is going. Your initial master sync should be clear, there is no way to see if it is done or running or completed the initial sync. Honestly, the master sync should be treated differently from intermittent syncs anyway. Now the containers on my old MBP are has changed to the original 5 or so default containers, all of my containers are definitely gone! I logged out of mozilla, since it is apparently breaking my good version of FF. Please clear up the documentation and include the use case of porting to a new machine to include Containers.