Several i have had issues where when I log out of my single player world and upon relog all progress from the last time i was in the world was gone.
The first few times it seemed to be from logging off on a horse and then relogging back at where I got on the horse.
Recently (10 minutes ago) I was working on a farm for dual spawners and I noticed nothing had spawned for atleast 3 minutes, so i relogged, and to my surprise I respawned in the location i had been an hour ago with all progress lost.
I don't have any screenshots because it is random, i wasn't expecting it and well screenshots wouldn't be much proof for this.