The bug

When you create a world buffet and you selected as world "Deep Frozen Ocean" with the generator of the world "Floating Islands" of the floating islands are generated with trees, everywhere with icebergs on the surface of rivers of water and lava and structures on the surface.
When you select the world generator "Surface" everything is normal.

How to reproduce

1. Create a buffet world generation
2. Select as biome "Deep Frozen Ocean"
3. Select as the world generator "Floating Islands"