General strange issues (very few chunks generate) with superflat in 15w31b

15w31b does not get along with superflat. I just made a Survival superflat world with the following preset:
3;2*minecraft:lava,55*minecraft:stone,5*minecraft:dirt,minecraft:grass;1;village(distance=9 size=3),decoration,lake,lava_lake

I EXPECTED:
it to generate an epic world full of villages in the plains.

I GOT:
it to generate only like five chunks. F3+A did not help. I jumped off the loaded chunks for a lark and sunk until the debug screen said it was at Y=-0. I then walked back into the loaded chunks (the above preset makes the bottom two blocks lava) with no problem, and fell through the lava into the void. I survived over 2 kilometers into the void. What is more, when I saved and quit to title, Minecraft crashed.