Tag 'folders' in left pane disappear

Tag 'folders' in left pane disappear

I created a few tag folders ('tag' > 'add to left pane') yesterday which worked fine. I've now logged in and all my docs are still in my account (phew!) and the tags are still applied to all the individual docs but there are no tag folders. Do I have to do something to make the folders persist over sessions?

Cheers,
James

Ps. It would be cool if I could share a whole 'folder' too ;-)