Light-emitting blocks have no effect on the light level of an area.

In both my creative world (created after the update using the amplified option) and my survival world (created before the update), torches and other light emitting blocks seem to provide no light. Instead, the appearance of light in a room or cave is caused by the day/night cycle. I am almost certain that this is a visual bug, because no mob spawning is occuring in the places that appear dark, even with the "Mob Spawning" option on and the difficulty set to Hard. All worlds that I have are affected by this bug.