Weird lights but only at a certain location

[sonicf86 (Zsubi)]

I am trying to decorate an area but the lights are acting strange, like this:

(Right side)
But if i move the light 10 studs away from that location it goes back to acting like a normal light, like this:

Does anyone know how to fix this issue?

[pulse_tech]

Is the wall a union or just a part, and is it parallel with the other wall?

[sonicf86 (Zsubi)]

The wall is just a part, but i don’t think the walls are not causing this because the light acts weird even if there are no parts or anything in a 20 stud radius.