Falloff map for BoxLights?

[Tomlacko]

Hi, in my custom story, I'm trying to have a well-lit area (using a box light) and some dark tunnels with no ambient light. The problem is the border between the lit and dark area. I tried using the falloff map option on the BoxLight (and on other box lights to test it) and it just doesn't work, I also checked in-game to make sure.

So I'd like to ask, do falloff maps not work for box lights at all? And if so, what can I do to make a transition between the two environments?