I don't think I've mentioned this before. (Hopefully - not trying to harangue you or anything like that.)
When you set up a scenario SM you have two options: Add and Remove.
When you play a scenario you need a third option: Update (which simply redoes the add feature using the same name)
Also, it would be nice to have a copy option, but Add can be used for the copy option so - it's just a convenience routine. Also a Rename feature would be nice (combines Remove and Add). Again, this is a convenience routine. But the Update is really needed as you can keep track of a party's mask by updating what they see so it is stored for the next time you play.