I'm on a mac desktop and running Firefox 21. I want to import the bookmarks from my laptop and so I have tried the following without any success.:
1. Saving Firefox Bookmarks as a HTML file and using Import Bookmarks feature in 'show all bookmarks'
2. Use sync to sync both machines.
On each occasion, using both methods, I can see the bookmark structure but only the folders seem to be imported and when I hover over the folder the message 'empty' is displayed.
I'm not sure what else I can do but it seems that Firefox will not actually import its own exported files from and identical version of Firefox: 21.
You can check for problems with the places.sqlite database file in the Firefox profile folder.