I have a world which was made before bedrock edition was portes to PS4. The world was a superflat. Logged on today after the new update to find the world had literally vanished. Every chunk has gone missing. The only thing that remained was a Giant glass dome which I had built at Y level 169.  

seems like the new beta tried to increase the world limit but didn't factor in my world was old, which pulled every block under the bedrock barrier and destroyed it.

please help me! Happening to others too.