[MCM-1835] World templates can rarely generate a void world and fail to load all resources which then affects all maps (Void World Bug)

Verification Builds{}
All builds since somewhere in 2023
RARE CIRCUMSTANCES, HARD TO REPRODUCE BUT AFFECTS MANY CUSTOMERS

Summary:
When loading into a world, sometimes no blocks or land loads in at all and the db appears to be wiped with a total void world. The player falls to their death and respawns only to fall again. In addition, all files from the pack are not parsed properly and throw errors on line 1, column 1 of their files. Once this occurs, it usually prevents world template creation for ALL templates until resolved. More info follows.

Since we first encountered it in 2023 when developing Universal Studios Experience, the "Void World Bug" has been damaging our business and reputation as it has gotten worse over time. At first it was only seen with Universal, then we started to see it with Dungeons & Dragons, Disney, and now we're even seeing it in third party maps such as Mutant Caves (which recently failed cert for generating a void world, the first time that's happened to us).
This bug takes many different forms and has been reported as separate issues many times, but I believe it's all the same problem and needs to be consolidated and looked at more closely.
Other terms/names this bug has been reported as: "When creating a marketplace world, two worlds are created." This is only true sometimes when reproducing the issue and therefore does not fully represent the scope of the problem.
"Vanilla World Bug. When creating a marketplace world, a vanilla world is generated instead." - This is different behavior than we've seen from actual customers. We've not seen vanilla worlds get generated but instead void worlds. However, it is possible these issues are related. In addition, we have seen this issue occur when creating a world from a template directly a realm but never locally.

In the past, when we have raised concerns about this issue, we were instructed to gather the Xbox Usernames of customers who reported this behavior. We have since provided somewhere around 100 names, I think. I'm not sure where that investigation was going or if it is ongoing.

Links to Other Discussions on this bug internally at MS:
Link to a slack thread in Support regarding the bug as it relates to DND.
The above thread talks about the bug as "Vanilla World Bug" and may or may not be related.
Slack thread in firework_qa
Universal Studios was even affected by this issue so frequently on switch that a special message had to be put in that announces to the player to keep recreating the world many times to fix it.

User Impact:
Extreme - Players purchase an empty marketplace world and it often makes the rest of their entire game and all their maps unplayable. After it occurs once, often every single other template from any studio that is generated will now generate an empty void world. This cannot be fixed with relaunching or even redownloading. It often takes many new world creations to make it stop if ever. Or the player will need to reinstall their game completely. More info about how the user can address the problem can be found in sections further down.

It is important to note that this can occur even on local worlds and does not necessarily have to be downloaded from the marketplace. We have only seen this demonstrated when testing Universal Studios Experience locally on a switch console ourselves. Other than that, most of our data points are from live marketplace content.

Repro Steps:

Unfortunately, even after months of research, we cannot find reliable reproduction steps for it. But we get hundreds of complaints from customers. We have concluded that the only reasonable way to attempt to reproduce this issue is through mass testing. Attempt to download and create the world in retail from many different devices through actual use and hope one encounters it. I know that this makes this bug extremely hard to address, but in our seven+ years in the marketplace, we have rarely, if ever, seen such a prolific and common critical bug as this on such a wide scale which has lasted for this long.

If it occurs, these are the steps:

Download the world template from the marketplace
Attempt to create the world
Upon the world loading, you will fall into the void and die in a world with no blocks.
In addition, if you have content log errors on, you will get a content log error for every single file in the pack claiming it can't be parsed.

Theories on Reproducing the Bug:

Although we have not found conclusive evidence, we have a few theories on ways to increase the likelihood of encountering this bug:

Play complex maps (like Universal or DND) on weaker devices like Switch. Based on our large sample of user bug reports on our maps, these seem to be the most commonly affected devices. Although, interestingly, it does seem to depend on which map is affected (although this may speak to an individual maps' popularity). For example, we got many more reports of this issue in Universal on Switch but more reports on PC for WDW (although far fewer).
Already be using a lot of storage for Minecraft. Have lots of active worlds and have many templates installed. The bug may be more common on heavily used systems.
Test in a retail environment. Perhaps due to our restricted sample size (that is to say, far more people play in Retail than NOT), it's possible this issue occurs more often on Retail.
Interestingly, even though we've mostly only seen this issue get started by complex maps, even a very old map we just updated minorly, Mutant Caves, failed Certification for triggering the void world bug.
Please note that this can occur on more worlds than just those by Everbloom Games. We have heard from other customers in the past, although we have not had the reason or ability to reproduce ourselves on maps that are not ours.

Observed Results:
Player falls into void and dies in a loop. No blocks are present. All files throw content log errors and fail to be parsed. On lower end devices, sometimes you will even crash before dying.
After this initial incident, roughly 90-100% of the time it occurs, this bug now occurs on ALL world templates. Meaning that even after relaunching, the next time the player tries to create a template from ANY world, they load into a void world again. From our testing, there seem to be no exceptions to this when it happens, regardless of the age of the map or complexity. This even further sours the user's marketplace experience and the reputation of the market. Please see the next section for information on how to remedy this situation as a user.

Fixing the Issue for the User:
Typically, the only fix for this for the user has been one of the following (not consistent):

Reinstall Minecraft (always works)
Keep trying to create the world from a template. We've seen this work between 4-55 tries; an enormous and unreasonable range to expect players to keep retrying.
Deleting all worlds and templates, relaunching, and then redownloading and attempting again (only seen this work once or twice, I think. Not confirmed).
If the user has access to their game files, like on PC, deleting the contents of the "logs" folder located at C:\Users\USERNAME\AppData\Local\Packages\Microsoft.MinecraftUWP_8wekyb3d8bbwe\LocalState\logs and relaunching. (I have personally only tried this once, but it worked flawlessly. I suspect there is something significant in that, I have attached the content of my logs folder when I did this in my test (exceeds 10mb, please ask in slack). Note that, unfortunately, I accidentally combined it with a few files that were generated after the problem was fixed, so it may not END with the problem). Note that you cannot re-activate the problem just by dragging these logs back into your folder.

Things I tried that have not made a difference in trying to fix the issue once it occurs:
Relaunching minecraft even after multiple times
Switching between old and new UI settings.
Changing render distance settings.

Expected Results:
World templates load normally.

Attachments:
Video of issue (ask for attachment)
Logs from the log deletion test (ask for attachment). Note that you cannot re-activate the problem just by dragging these logs back into your folder.
I've also attached 5 log files from my game directly after encountering the issue in case the zip is out of date.