Indirect Ligting Saturation "Bug"?

hey,
It seems that they are some problems with the “Indirect Lighting Saturation” option on spot lights.
Even if i set the value to 0, the scene looks excartly the same like with the standard value of 1.
Im not sure if this issue is just on my side or a generall bug…

I had the same issue, it’s a year already, any updates?