Existing worlds corrupting after time has past destroying progress

Partner Rank: 1
 (No work around)

Verification builds:
1.16.1

Summary:
This issue has been occasionally reported on multiple devices across multiple maps, since December 2018

Players report that after playing maps for sometime, ranging from weeks to months, they return to their world to find any progress gone or the world completely replaced by a blank flat world. Attempts to restore the world often fail leaving the player distraught. In a recent report we were sent a copy of the world file (find attached to this report) Upon investigation we found that the level.dat file had corrupted and been wiped, destroying any chance of rescuing the data.

We have no recommendations to fix this issue. We can only suggest reinstalling the map in question and starting a new world, with no promise that it won’t happen again.

As we've been unable to replicate the issue in any of our tests, I've compiled the reports into one document with all the details I've been able to gather.

Impact:
We received several emails from player reporting worlds and any progress made on them disappearing or being replaced by a superflat world after long periods of play. Since we couldn't reproduce it, we've compiled a document which we are continuously updating with reports.
This document is linked in the mco-noxcrew slack channel, Greg and Quinn should be able to get the link.

These consistent crashes will result in lower ratings, negative social media, more customer complaints, undue player distress, and potential refunds.

Repro Steps:
Unknown

Observed Results:
Maps disappearing or being replaced by a superflat world after long periods of play

Expected Results:
Maps shouldn’t disappear or be replaced by a superflat world after long periods of play

*Screenshots/Videos attached: * Yes