I am playing minecraft 1.8 vanilla while creating a mob spawning room I have used commands to fill the required blocks. the room seems to be complete but with one issue. you can see the light level 15 in the snapshot. However the room is totally concealed.
When I fill the blocks manually the light level goes down to 0 as expected.
so by using fill command why does the light level does not fall to 0
/fill
commands don't cause lighting updates. You could try spawning aFallingSand
entity and having it fall into a spot on the floor (setblock X Y Z air
and thensummon FallingSand X Y Z {Block:"minecraft:your_block_here", Damage:?, Time:1}
)