When building blocks, exiting to menu, returning to the world: the blocks changes arent saved

When i play on my survival world i made some changes and when i exited to the menu and returned back to my world, the changes arent saved and i lost my blocks.

What I expected to happen was...:
This shouldnt happen and i keep losing my blocks all the time.

What actually happened was...:
I lost all my blocks

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
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