When placing any kind of variety of vehicles in the editor, AI will try to rearrange themselves if you order them in file formation, regardless of their placement, rank, or other info. They usually try to get in a descending order from MBT to unarmed car. If you put them in this order in the first place, then the AI will still rearrange themselves. This can be very frustrating to have to wait for the AI to do this, and it also messes up your plans as to say, have a certain lead vehicle and vehicle protecting in the back, as the one in the back will try to go up front.