Yesterday, in a successful attempt to play cross-platform, I signed in to my Microsoft account for the first time from my iOS device. I had to go through the process of creating a new gamertag (which it did not honor, and changed back to the imbecilic default one as soon as I hit "done") for Xbox. 

Fast-forward to this morning, when I attempted to start up my main survival world, and it informed me that it had failed to load. Feeling nervous, I tried again, and although it finished loading this time, I found to my horror that it had completely wiped all of the progress from the world. I spawned at the original spawn point, with everything just the way it was the first time I had opened the world. I signed out from my Microsoft account and tried again, to no avail. I've never made a back up because I've never done anything risky. I've only ever used the product the way it was designed to be used.

It doesn't need to be said that I'm deeply frustrated and disappointed. No small amount of work has been lost.