Hi, am not sure if this actually happened, but from seeing my game recently, and reading other posts, it makes me wonder…
did someone raise the height (offset) of the ground level, up a bit (possibly by click-dragging by mistake?) i ask this because in some areas (desert sand floor, or near islands, or on top of rock) npc characters and some buildings look like they are partly sunk into the ground.
maybe this is also what causes some characters or npcs to vanish into the ground?