Adding/Removing a Material Layer on a Parent Material doesn't propagate to Children correctly

When a Material Layer is added to or removed from a Parent Material the layer changes don’t automatically propagate to Child Materials correctly even if the Parent Material is saved. The Child materials must be opened individually and the layer visibility toggled for the Child materials to show the new Material Layer in the Editor Viewport.

1. Open the MAP_MatLayersDebug_A level in the attached project
2. Open the MI_LayeredMat_Parent Material
3. In the Layer Parameters tab, add a Material Layer, set the Layer asset to ML_BasicLayer and the Blend Asset to MLB_BasicLayerBlend

Expected
Parent and child materials in Editor viewport update

Actual
Only the Parent material updates and reflects the new layer

Saving the Parent Material has no affect on the Child Materials

4. Open the MI_LayeredMat_ChildA and toggle the layer visibility in the Layer Parameters tab, and save the material.

1. Open MI_LayeredMat_Parent and delete the new layer that was added and save the material

Expected
Parent and child materials in Editor viewport update showing the added layer is gone

Actual
The MI_LayeredMat_ChildA still shows the added layer in grey.