DoomSquirter: I will look into why the fave bar is not refreshing after a enter/exit into a factorismo factory - stay tuned. I don't use factorismo normally, so it may take a bit to get up to speed. This sounds like it might be a factorismo issue where it is not refreshing the UI after enter/exit
Zaanzabar: I think you are deleting with vanilla map tag modal. There is something wrong in that the favorites are not being updated after a delete from that modal and I will work on it and get back to you. In the meantime, instead of doing a left click on the tag to open the modal, use a right-click to open this mod's tag editor modal (you will see the diff because the favorite button appears) and the correct actions should follow.
Thank you both for reporting these issues.