My game froze up and crashed, which wasn't a big deal. It's happened before. I reloaded the game, expecting it to pick up from near where I left off.  I ended up resuming from the spot I was in a few minutes before the crash, and was immediately told that I had reached the achievement "Cover me with Diamonds". Which was strange because the set of diamond armor I had was weeks old. Confused, I looked into the advancements tab and to my surprise, it was wiped clean. All the advancements were not completed. Same with statistics. everything was just zeroes. All my stuff and progress was pretty much, unhindered, but it was kind of a bummer to have all the advancements wiped. 

Steps to Reproduce:
1. Have a game crash in the new snapshot, if possible
2. See if the game resumes where the crash occurred, or if it picks up beforehand. 
3. Check to see if advancements have reset or not. 

Edit: Loading a backup fixed the issue.