Put the summary of the bug you're having here

What I expected to happen was...:
when I exited to menu, I thought everything I made would be saved

What really happened was...:
All recent blocks/items that I had placed disappeared and were not in my inventory, all stone utters replaced with two furnaces(one where it was, the other in inventory), and any smooth sandstone I placed was replaced with regular sandstone

Steps to Reproduce:
1. Place stone cutter, place smooth sandstone, place blocks, kill animals
2. Exit to menu
3. Resume map/world
4. Everything gone/animals not respawned...