Custom Primitive Data are not (fully) functional with Instanced Static Mesh components

If the ISM component is not in a blueprint, but added directly inside the level, the CPD works. If the CPD value is set from a construction script through either the Default or Transient function, it also works. The issue is exclusively with ISM components, inside a blueprint, with their Default CPD value set inside a level.

In the provided assets, open the level and you will see two setups, one made from blueprint, the other directly inside the level. If you select the ISM component on both, you can see that both have their CPD value set properly. Yet only the blueprint actor ISM_BlueprintActor remains black, intead of the expected yellow value visible on ISM_LevelActor.

Repro Steps :

1) Create a new Actor blueprint

2) Add an Instanced Static Mesh component, set up its mesh, a material using Custom Primitive Data, and populate the ISM with at least one instance.

3) Add this blueprint to a level

4) Set a Default Primitive Data value on the ISM component.

5) Notice how the ISM does not use the provided CPD value.

Expected result : the ISM should use the CPD values.