I have been using Minecraft Bedrock Edition for quite a long time now, and have previously had no issues. However, once I opened up the game on May 1st 2020 the world I had been playing on the previous night had disappeared. I tried looking at the world storage within the game, however it was as if the world that I had been playing on didn't exist. Reloading the game at this point also didn't help.

Then, believing that it was a one off event, I then created another world to replace that one and went about my day. However this morning (May 6th 2020) I went on my Xbox One to discover that the same thing had happened again and the subsequent world had also vanished off of the Xbox without a trace. At that point I uninstalled the game and then reinstalled it, but that failed to change the list of playable worlds in any way.

However, I'm not sure how you would be able to replicate this, aside from creating a world on the Xbox One version of Bedrock and waiting a few days. My apologizes.