Entities are despawning after closing the game without saving or when the game crashes

[1.13]
Partner Rank:
1

Partner Team Reporting:
Everbloom Studios

Verification builds:
1.13.0.7 - 1.13.0.6 - 1.12.0.27

Summary:
Entities are despawning after closing the game without saving or game crashes

Impact:
This bug affects many live maps and I used The Enderman Heists as only one example. This is not an issue with that particular game.
These maps are at risk of permanently and irreparably breaking at any moment.

Repro Steps:

1. Open a copy of The Enderman Heists from the Minecraft Marketplace.
2. Walk over and push the button labeled Start Tutorial
3. Walk forward and get caught by the Enderman to move to the next level
4. Walk forward and make a right, then a left. You will see an Enderman facing the wall in front of him.
5. Crouch past him and turn to the left and observe the Enderman walking in a circle.
6. Close the game without saving
7. Re-open the same map and repeat steps 4 and 5
8. Observe the missing entity.

Observed Results:
The Enderman that was there is now gone. On other maps, like A Nightmare in Candyworld all of the entities in King Candy’s courtroom disappeared. Worst case scenario (if an important entity is despawned), the map is permanently broken and must be recreated from the very beginning.

Expected Results:
The entities should not despawn when the game crashes or is closed without saving. The player should be able to continue the game without having to reinstall the map.

Screenshots/Videos attached:
Yes

Regression Builds:
Unable to test in builds prior than 1.12.0.27

Notes:
I tested the following marketplace content

• A Nightmare in Candyworld
• The Enderman Heists
• Crazy Town
• City Living by Noxcrew
• Dinosaur Island by PixelHeads
• ANIMALS
• Unannounced project

On all the following maps the entities in the game despawned after the game was closed without saving.

• A Nightmare in Candyworld
• The Enderman Heists
• Unannounced project

Maps: City Living by Nowcrew, Crazytown and Dinosaur Island by PixelHeads remained unimpacted. ANIMALS also appears to be unaffected.