EDIT: INVALID ISSUE. MCedit caused a heightmap problem, it seems.

I was making a few caged worlds with barrier at the walls and the ceiling until I noticed this bug. When a chunk is unloaded, the terrain/land/chunk thinks that the barrier has a shadow, henceforth when loaded I got a blackened chunk.

Steps to reproduce:

1. Cage a chunk (y chunks do not matter) with barriers. You need to cage the ceiling of the chunk too in order for this bug to show up.

2. Go far away where the chunk goes past your render distance (e.g. not able to see the chunk anymore)

3. Reload the chunk by going to it again. Whatever is in that chunk is now blackened until you go around it and all of the lightning loads again.

Included some pictures.