Yeah if you turn off experimental 3d vision, but leave z-levels on, that will stop happening. It’s an unfinished feature, so that seems to happen. I once tried it and had an NPC just shoot all his arrows at the ground trying to hit something in the subway(i guess) below. It confused me a first. I could draw him away give him his arrows back and would forget about the spot, but every damn time we went by there he would just unload lol, I eventually turned it off, but leave z-levels on. Sometimes you will be crafting and it will say something it spotted or approaching, but it’s actually not… it’s just on the upper or lower level.