Tom, The whole "Favorites" bar and related bits from that add-on are set up such that they access the Favorites list from IE itself and make it accessible inside of Firefox. The Add-On was created quite a while ago and both IE and Firefox have been updated many times since then. The latest version for the version history shown on that page is for version 1.3, designed to work with Firefox 22 and the current version of Firefox is 43.0.4. I am not surprised that some of the features are not working anymore and my guess is that unless the developer is willing to make a new revision to work with the current versions of Firefox, IE11, and Windows that you're not going to recover the functionality you're looking for.
You could always write to Alex Sirota and see if you get any response. Otherwise my advice to you would be to start using the Firefox Bookmarks system exclusively. You can import them into Firefox Bookmarks directly from IE. See this Firefox Help Webpage on Importing Bookmarks from another browser. Brian
