Setting Sky Distance Threshold to 0 in a Skylight does not disable the light

When setting the Sky Distance Threshold to 0, the skylight in the level appears to make the level brighter instead of disabling the added light.

This does occur in 4.16.2 and 4.15.3

1. New Blank Project
2. In the Modes Panel, select Light
3. Click and drag a Sky Light into the level
4. In the details panel of the SkyLight, set Sky Distance Threshold to 0.0

Result: The floor in the level actually gets brighter

Expected Results: The floor in the level looks as if the SkyLight was turned off or deleted