It is a bug if a killed zombie did not reduce the sleeper volume count. Seeing them in different spots after despawn/respawn is how it works right now.
Here is one issue with that system.
Why can I not just attract the zombies and lead them out of the house?
I know the explanation was to prevent Pied Piper clearing of POIs.
However, previously the justification of forcing the kill to be in the sleeper volume was rationalized by at least you get loot to offset the risk and expense of resources in doing such.
Now we still can't do as any sane person would do and lead the zombies away because they won't count as kills to the volume, but we also don't gain the reward.
Just another thought on the change on loot factors and how it impacts Sleep Volume balance issues.
Sleep Volumes also tied to Gamestage where more keep spawning once you've reached a higher Gamestage was also rationalized by at least one gets loot. So again, another area of the Sleep mechanic that should be revisited. This was especially bad at high Gamestages in mid-size and larger POIs. It was this that usually made the issue of "I cleared the room, walked out and back in and it was full again" even worse.
I'd have to hope POIs are going be rather loot heavy in their containers to make them worthwhile. Maybe some kind of Loot Volume system that works similar to the Sleeper System and uses Gamestage to keep it all balanced out. That of a significant decrease in the sleeper volume spawn numbers and Gamestage influence.
Note of course this all goes based on the A16 Gamestage system which means some or all may be inapplicable already.
Just babbling based on what I've experienced in A16 and seen of A17 in MM's video there. Obviously you all have probably thought these things through already. Heck, anytime I think of something someone has already thought it, or done better and solved the issue.