Niagara: Skeletal Mesh Location : Filtered Bones not working?

Particle spawn by Skeletal Mesh Location with Mesh Sampling Type: Bones (or Sockets) does not work with Filtered Bones. I’ve created a sampling region containing bones on my skeletal mesh, and these work when setting Mesh Sampling Type to Triangles. Any1? Bug?

Under Bone Socket Index, you set this to execution index

You have to set the “Triangle Sampling Mode” to “Random (Sampling Regions)” for this to work.