I was just playing in my survival world (Created in this snapshot (12W31A))
when i put the chunk loading up to 24 from 14 it started to go all weird.
When i Put it Below 16 Chunks (like you usualy could) It still does it.
I have it back on 14 Chunks now and i see this (The image).

This might be because I am pretty high up. (Y 218)
I hope you can Fix it! Gl Guys!

Greeting's
Alwin (The Netherlands)

Btw.
I love your game even after about 5 years.