

My assumption on it is that the files wern’t synced to begin with. I looked the issue up on the site’s discussion area and it looks like it had a major sync issue a few years back where it wasn’t always syncing folders automatically and completly so files got left out.
As someone who went through the 12-13 upgrade last week. Do not go directly. I had to rollback twice during the 12-13 upgrade(thank you timeshift) so I couldn’t imagine trying to run an 11-13 upgrade.