[FR] Corrupted Lots/Houses disappear in saves with lots of rental units

So after poking around a bit with Sims4Studio in my save file... I think I may have found a possible reason behind the save corruption - specifically when lots suddenly become unplayable, missing, or get stuck on an indefinite loading screen.

While looking through my save data, I noticed a consistent pattern:

• Lots that are Rental units have a Zone Object Data file of only 9 bytes.
• These lots appear to store their object positional data inside the parent lot instead. Makes sense.

However, the specific lots that have become corrupted in my save also now show 9-byte Zone Object Data files, even though they were originally regular residential lots. 

Looking at the raw data inside and we see it's identical to the entries for subrentals:

{
  "ZoneObjectData": {
    "zone_id": "0x07220ABB345BB1A3",
    "architecture_data": [],
    "objects": [],
    "sub_venue_keys": null,
    "active_data_index": 0,
    "is_modified_from_lot_template": false,
    "architecture_bundle": {
      "U1": "0x00000000",
      "U2": "0x00000000",
      "Records": [],
      "Version": "0x00000001"
    }
  },
  "DisplayName": "Oasis Springs: Nookstone",
  "TypeName": "ZoneObjectDataResource",
  "Key": "00000006-00000000-07220ABB345BB1A3"
}

Note: A normal empty lot (i.e. one that that has been bulldozed is not this minimal and still contains a lot more data than this).

Lots that are unaffected and play normally have Zone Object Data filesizes of between 50kb and 2MB which makes sense given complex builds.

(I won't paste the contents of the data here as it's huge but needless to say "architecture_data" and "objects" are all populated out with all the positional data)

This suggests that at some point, the game overwrites or misflags these lots as rentals, but without any valid parent/child data relationship.

When that happens, the game can no longer find the expected object or zone data for those lots. Resulting in broken or missing lots, failed loads or resorting to using game defaults.

Interestingly, in my save, three worlds have been decimated by this corruption: Oasis Springs, Del Sol Valley and Magnolia Promenade. All other worlds were unaffected. Unfortunately though, poor old FutureSims Labs was also zeroed out by the issue. No more active career for my science sims in this save it looks like!

So in short:

It looks like the game is mistakenly treating normal residential lots as rentals, wiping their zone object data with a non-existent link to presumably a parent lot which the game cannot find or doesn't contain relevant data.

I have no idea what causes this, but I would imagine it happens at the point of the game writing lot data to the save file. 

If anyone from EA or the modding community can confirm whether the game re-uses the same data structure for rentals and other lot types, it might help narrow this down. Hopefully this information will come in useful to someone.

Unfortunately if my findings are correct, it does look like this kind of save game corruption is irreversible, so the Memory Boost may already be addressing this issue but it was unable to rescue my existing save because the data is already gone.

Again, EA/Maxis. Please talk to us and be honest if this is the case.