I have second-level walls, and when I learned level 3, their level didn't update, it only affected the new walls. In addition, the next day the save was no longer loaded, giving an error:
Error while running event AlienWall::on_configuration_changed
AlienWall/control.lua:53: attempt to index local 'newWall' (a nil value)
stack traceback:
AlienWall/control.lua:53: in function 'upgrade_gate'
AlienWall/control.lua:92: in function 'update_walls'
AlienWall/control.lua:63: in function <AlienWall/control.lua:58>