I've been using Xmarks for years without problem using Firefox on a variety of Windows and Macs. I've many RSS bookmarks.
Recently, I bought a new MacBook Air and installed XMarks for Safari on it. This sync'd and now all my RSS booksmarks just say "empty".
I thought, "Well OK, Safari bookmarks don't support RSS". So, I set Xmarks for Safari to only sync manually and I'll only "download from server".
However, my problem is that I can't get my RSS bookmarks back in Firefox on my Windows computers. I've tried restoring from old Bookmarks Sets but they aren't coming back.