There is a bug that strongly breaks usability: when I move Thunderbird Portable to another PC, it doesn't remember which folders has "Favorite" mark. Also, I have "Favorite" option set in View - Folders menu, but it resets to "All" on another PC. Some folders occasionally lost Favorite mark even when I move Thunderbird folder within 1 PC.
It would happen for both folder and PC changes as it's likely tied to a path change. I don't use Favorites myself in TB but I think I had fixed this a while back. I'd wager TB changed the way it stores them. I'll need to look into it as soon as I have time.
Sometimes, the impossible can become possible, if you're awesome!