I want to add my own theory onto this
Think of the game world as a 3D box (which it is)
a 3D box with many layers and Each missions has Layers of their own in different locations
The "Dungeon" for example, its PlayZone layer is roughly around here, high above the skybox
View attachment 4085762
Why do I suspect this?
I got a nice
old base around the
play area and I keep seeing "training" "log" "livestock" "harvest" icon popping up for me when I went into the
Dungeon, after a while those icon disappear and does not appear at the same spot
I think what happen is the
game aren't suppose to show those icons while you're in the dungeon, but those icons will "float" into the player's screen from off-screen map, so when you move around the Dungeon level, those icon takes sometime to disappear from view.
View attachment 4085731
So yea, minor inconveniences if you set your base near the Dungeon or the middle of the map
The other places has their own layers OR just on the same layer as the Overworld
The Gate/Tunnel section for the Three Gem is a good example as it's just slightly lowered layer to the Overworld,
Ask a NPC to follow you and you can set his/her movement near the inner Gate, when Scouts goes near the Gate, your Friendly NPC will detect them and go out and fight them...assuming people are like me playing with no invisible wall option on
(honestly it's more hard since you can't abuse it like where my Old base is, but you can use stone bench to section it off :3 )
The Lab area layer is slightly lowered than the Red Lab Gate, I know because I put the
Man's Son & Son's wife in the Lab area and every time I just see Two heart appear below the Red Lab Gate xD