World loading screen freezes when a new customized flat world is created

The world loading screen freezes 99% of the time when I create a custom flat world. Please fix. Very annoying because I need to open task manager to kill the task because the game won't close when this happens.

What I expected to happen was...:
When I create a custom flat world, the world should load.

What actually happened was...:
Instead, it freezes 🤬.

Steps to Reproduce:

1. Create a world
2. Select "super flat”, click “customize” and then choose “redstone ready”
3. Create the world
4. There is a 99% chance that the world will freeze while loading.

Refer to this YouTube video for more info:
https://youtu.be/aVTODn3zo8M