Hey Shora, why are the vertical shadow areas lighter than the horizontal shadow areas?
I am using version 1.8.3. The same error also occurs in 1.9.4 (with the added issue of lights "turning off" when I get too far from them)
As of now, I can't use the shadow system.
I'd be grateful if you can provide a small demo, or at least a map that demonstrate the problem for me, that would certainly help me fixing your problem. Currently I can't recreate the problem on my side, sorry!
Was this ever resolved? I'm having the same issue, strangely enough.