Whenever artifacts disappear from the screen and the "edit settings"-button is not the cause, they can't be placed on the map again before saving and reloading the map.
How about a "redo"-button?
When trying to adjust a stack that stands on an artifact, the artifact has to be removed first. Same for cities. Can't adjust them without taking away units on top of it (if they cover all four squares). You have a handy "item/building/unit"-thingy in-game, would it work in map maker too, you think?
Will stacks put out on map go into battle the order they were set, or will they follow regular battle orders, with heroes on top etc?