Blend Weight do not work anymore in Post Processing Volumes. UE 4.11.2

Latest answer just solved my problem ohhhhhhhhhh happy happy so happy
I don’t really understand but I caught the eureka moment!!!
Let me guide you lost soul–

  1. Make sure your father material has an ultimate exposed parameter that blends the PP effect with scene texture
  2. Set the default value of the Param in father MAT to ZERO
  3. Create an instance MAT and set the value to ONE
  4. The blend value in PP volume now magically works!!!