Incorrect Generation Of Bone Blocks And Coal Ore In Underground Caves in Swamps

Put the summary of the bug you're having here

What I expected to happen was bone blocks and coal ore to generate in walls for cave generation in swamps

What actually happened was bone blocks and coal ore were generating in mid-air

Steps to Reproduce:
1. Search underground in a swamp biome in spectator mode
2. Travel around for a few minutes
3. Before long you would have found the bug