The Code in ChunkSelection.java that reports if a specific part of a chunk needs to be delivered to a client or not is faulty:

public boolean a() {
return this.nonEmptyBlockCount == 0;
}

The code does not consider the fact that - even if there is no block in a chunkselection - there may still be light-information for that selection.

This results in light-Bugs on the client side if a Chunk hast light-information in a chunkselection that does not contain any blocks.

The screenshots show the issue very well. The missing light-information is clearly visible. The faulty chunk has blocks exactly up to 63. At 64 a new Chunkselection starts and the light-Information stored in that selection are not delivered to the client

This can be fixed by changing the code:
public boolean a()

{ // return this.nonEmptyBlockCount == 0; return false; //kade fix, bukkit reports wrongly if a part of a chunk is empty or not. }