I'm not sure how to explain it, I think its a certain range of chunks that make the game crash and not load properly. I'm assuming its because there's a significant amount of chests, but other areas seem fine. The chunks never crashed until this most recent patch.
McDonaldFork 
MCPE-79960
Oceanic mobs can no longer spawn in bubble columns (magma blocks and soulsand).
I'm not sure how to explain it, I think its a certain range of chunks that make the game crash and not load properly. I'm assuming its because there's a significant amount of chests, but other areas seem fine. The chunks never crashed until this most recent patch.
You're in a version where there's no dedicated servers so you can't play on them until you either leave the beta or the full release comes out