This is a misconception, it's not the physical asset that's disappearing, it's the randomizer working as intended and this being a side effect.
If you pay attention the asset itself is still there in the same spot but a different randomized version of it appears in it's place.
For example, if you have a green Thorton Galena behind you at a certain distance and you spin the camera around slowly a different Throton Galena takes it's place.
It's the same thing with the NPC, if there's a female NPC waiting to cross the street and you spin the camera around a different female NPC takes it's place.
The asset culling works but it's a few cells away from V, so not really in your face, the problem is, it becomes really apparent when the pathing breaks and there's a traffic congestion some hundred meters away from you and you spin the camera around the traffic get's itself sorted because the problem assets get culled out.
So it's really a multifaceted problem that has some degree of features that need to be either redone or adjusted based on the algorithm behind them (AI pathing, asset culling, asset randomizer).
True and replace the npc mesh every time wastes a lot of resources :/
in this case with vehicles, with pedestrians it is worse
It occurs to me that it is not that the npc actors really disappear or are destroyed but that they have a simple patrol and that they turn on and off the visibility and collision and randomize the mesh.