logged into my world lost half of my progress

Put the summary of the bug you're having here

*What I expected to happen was to log back into my world to start my next project. *
Describe what you thought should happen here

What actually happened was logged back in and half my stuff i did was gone.
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. logged out of my world then joined back in and my progress was gone.
3.