I had the very same problem and after many hours of jacking around with this I found something that works. So you may try this and see if it works for you.
Edit -> Preferences -> Synchronization -> Clear
Edit -> Preferences -> Add-ins -> Synchronization
Disable them all and exit tomboy.
Restart tomboy and Enable "Local Directory Sync Service Add-in"
Then go back to:
Edit -> Preferences -> Synchronization and use Service: Local Folder and add the Folder Path.
The Local Folder works after doing this. The problem was that once I got it working it always works even if I enable the WebDav and Web Sync Add-in. So I don't know what causes it to break, but this was the fix for me.
I had the very same problem and after many hours of jacking around with this I found something that works. So you may try this and see if it works for you.
Edit -> Preferences -> Synchronization -> Clear
Edit -> Preferences -> Add-ins -> Synchronization
Disable them all and exit tomboy.
Restart tomboy and Enable "Local Directory Sync Service Add-in"
Then go back to:
Edit -> Preferences -> Synchronization and use Service: Local Folder and add the Folder Path.
The Local Folder works after doing this. The problem was that once I got it working it always works even if I enable the WebDav and Web Sync Add-in. So I don't know what causes it to break, but this was the fix for me.
Hope this helps.