Basically, I just died in the plains biome, and my friend told me "Your tombstone just disappeared". I got back to the place of my death, with the icon still on my map, and my tombstone was literally deleted from the server. All my silver gear, my 950 gold Mejingjord belt, all my stacks of food, weapons, every single thing in my inventory deleted. I've now lost hours upon hours of hard work and don't really have any further desire to play the game.
At the very least I wanted to report it here so it hopefully doesn't happen to people in the future.