I joined my cousin, who was on an iPad, on her world, using our Xbox accounts. We did not use LAN. After leaving the world, I was forced back to the title screen. I noticed that the background was black instead of showing underwater images from a Minecraft world. I was very confused by this. After exiting and re-launching Minecraft, this bug went away. I joined her once again and left, and this did the same thing. This is not a very major bug, but it would be nice to have it fixed. Thanks for taking the time to read this bug report.

(p.s.) If you were confused, yes, I can still press buttons and see everything except the background. Look at the image below if you want to see what it looks like when this bug occurs.