Unreal Engine Issues and Bug Tracker (UE-118904)

Steps to Reproduce

Create a material and a MPC
Add a vector in MPC and use it in emissive channel in the material.
Apply the material to a static mesh actor in the level and enable the "use emissive for static lighting" option of the actor.
Build lightmap and the environment will be lit by the emissive material.
Change the value of the vector in MPC, and build the light again, the lightmap will not change, until the material recompiled.

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Cannot Reproduce

Color changing through material parameter collection in a emissive material will not affect lightmap baking, unless recompile the material.