[MCM-896] Internal server desyncs from client, causes all entities to freeze in place

Partner Rank:

Partner Team Reporting:

Jigarbov Productions

Verification builds and Platforms:

1.12.0.28 Release 2555018 Win10
1.12.1.1 Release 2900603 Win10
1.13.0.34 Release 3406689 Win10
Summary:

Internal server desyncs from client, causes all entities to freeze in place

Impact:

This bug will force an upcoming map be unable to be released. There is no apparent reason for the issue and I've never seen it before in other projects but suspect the underlying issue could be the cause of something more widespread but hard to nail down.

Repro Steps:

Open the test world "muddy pig" from greggo on slack
Press the button to start
Kill the mobs
continue

Observed Results:

At some point, the mobs will freeze in place. It happens inconsistently and randomly, but does appear to happen consistently enough with this game mode to be replicated in a timely fashion.

When this happens, you are able to move around, but unable to interact with the world, use inventory, kill mobs, be killed by mobs. Basically anything. When you try to leave the game, it will hang on "Saving" and not actually save forcing you to close the client.

On reload, the world will roll back a little to a previous point in time, rendering the game mode broken.

Expected Results:

The game mode should continue as normal until the end.

Screenshots attached:

World sent to Greg including video

Regression Builds:

It has happened in every mode since development started. Am not able to go to older builds.

Notes:
I suspect it has something to do with the entities and behavior pack doing something invalid causing the game to break, specifically on the server part running the back end of the client.