I didn't remember much of them spawning under the floor but their body was unreachable so you would have to shoot them or go near them for a reaction. Most stairs in video games will keep going down by a few or two.Are they going to fill them in though? I certainly hope so but remain doubtful as SoD had similar issues. Remember when zeds would spawn underneath an infestation? As this is a problem that's rolled over from the previous game, I'm wondering if solving it is even possible or if this is indicative of some broader coding issue.