Transferred world and spawns jungle biome over half of creations

Put the summary of the bug you're having here

What I expected to happen was...:
I expected to see my world in this beta.

What actually happened was...:
When I came into the world I noticed that half of my stuff was replaced by a jungle biome. I synced this world twice but it gave me the same outcome.

Steps to Reproduce:
1. Step 1 (on home screen) select Play
2. Step 2 Sync Old Worlds
3. Step 3 select world to sync
4. Step 4 after world is done converting, click on world to load it up.