Structures do not complete animating on chunk unload/reload

Partner Rank:

 1

Partner Team Reporting:

Jigarbov Productions

Verification builds:

1.16.210.57

Summary:

Structures do not complete animating on chunk unload/reload

Impact:

Completely breaks Simburbia irreversibly and will result in millions of peoples maps being broken.

Repro Steps:

Open "Structure not working" test world (attached). 

1. press the button to start animating the structure
2. press the button to teleport away when it's in progress
3. wait a sec, then teleport back
4. also try reloading the world for an even worse result

Observed Results:

Structures do not complete if the chunks get unloaded.

simburbia video: https://youtu.be/pmlYSJoK6Eg

test world video: https://www.youtube.com/watch?v=AB4GUFYCSB8

Expected Results:

Structures should load to completion even through world/chunk reloads as they did previously

Screenshots/Videos attached:
above

Regression Builds:

1.16.100.04 - 1.16.201.01 This worked correctly, from 1.16.210.55-56 it would crash

Notes: