Hi, EnigmaGrey. Thanks for the reply.
That would suggest that what I'm reporting is indeed being caused by some form of data loss, or failure to save data. I forgot to mention that after the locking up was starting to happen this most recent time (it started to slow and a few seconds later became unbearable), I did press esc and attempt to close the game normally, and only after waiting for a while for it to close did I finally choose to open task manager and kill the process. However, the first time this happened, I definitely shut down the game properly, and I never saw any kind of error or anything. The second time it's more understandable that the surrounding zombies would disappear, because the game likely didn't have a chance to save things properly when I ended the task manually.
I'm running a 2060 with completely up-to-date drivers, however I'm on windows 7, which the game is supposed to support. I'm not really concerned about how it locked up my computer since I've played about 110 hours on build 41.55 and this is the first time that's happened. My main concern here remains the zombies around the player seemingly being deleted.
Now, if my completely code-wise-uneducated self were to suggest something, I would imagine the way the game is handling the saving of the zombies is in an order that isn't optimal. It's saving information such as where the player is located, the direction they're facing, or what their inventory contains, but failing to save the immediately surrounding zombies for unknown reasons. I would ask someone familiar with this bit of the code to search for what priority the game is assigning to the zombies around the player, as something seems to be absent there which is causing the game to fail to save them even though it had the opportunity.
I would rather the game revert me to an autosave 5 minutes prior, than to spawn me in with all surrounding 200 zombies gone. Nobody wants to play on a savegame where the progression and difficulty were altered to due this.
Like, imagine if the player's inventory were wiped instead. Or it sent them to some random forest/river at the coordinates 0,0,0. There's no reason the zombies should disappear, but for those things to not happen.