Lightmap resolution can't be set for Instanced Static Meshes ?!

Hi ,

I made a Blueprint that generates a Grid of Instanced Static Meshes using Construction Script. I tried increasing Lightmap resolution for the Instaned static mesh to get better shadows.
but When I build my lighting it doesn’t take Lightmap res into account and seems like it’s Locked !

As you see in the screenshot below : Green : Instanced Static Mesh with 1024 lighmap res / Red : Static Mesh with 1024 lightmap res ]

It’s seems weird , so any1 else faced this issue ?!