Reloading after a crash, map reverts, character doesn't

I connect to a host minecraft via LAN....2 of us play both on windows 10 pro.
1. Host Minecraft APP suddenly crashed....the app simply.instantly closed.
2. Restarted minecraft- by simply double clicking the APP again.
3. When logging in, our characters were in with the same spot, with the same levels and inventory as when the crash happened, but the physical world was reverted to about 2 hours earlier. Everything built and placed for the last 2 hours was gone. The host character actually appeared fully encased in cobblestone that was un-mined. The host character was taking non-stop hits, but no damage. I had to log on to the second computer to dig him out. We were both highly frustrated that everything we built for the last 2 hours was gone, even though our character positions and inventories were accurate up to the time of the crash.