Normal map problems light instanced material

Hi guys,

I’m trying to set up a master material for all my meshes that i create in blender and textured in subs painter; i create 6 atlases in subs designer for all my UVs with no overlap. When i Connect the normal node in the master material, lights are cut in half as you can see in the image.
The normal map texture is imported correctly (WorldNormalMap, compression NormalMap); in project configuration i disable ‘‘use Normal DXT5’’
I post this even in UE4 forum.
Please help me, i am a noob anyway.