Instanced static mesh component PerInstanceSMData array defaults do not propagate from the owning Actor CDO to instances on edit.

This occurs because the 'LightmapUVBias' and 'ShadowmapUVBias' struct fields (deprecated) are initialized in UInstancedStaticMeshComponent::SetupNewInstanceData() to nonzero vectors, but as these properties are now marked as deprecated, those values will not propagate from defaults to instances, which results the PerInstanceSMData entries failing the Identical() check between CDO and instance. That blocks propagation after the first entry is added because an Identical() failure normally indicates that the user has edited something away from defaults on the instance side, but that's not true in this case.

1. Launch QAGame editor.
2. Create a new Actor-based Blueprint class.
3. Open it in the Blueprint class editor and add an InstancedStaticMesh component. Choose any static mesh asset for the defaults.
4. Compile and save the Blueprint class (but keep the editor window open).
5. Drag an instance of the new Blueprint class into the scene and select it.
6. Select the InstancedStaticMesh component in the Actor details view. Note that the "Instances" property contains zero elements (matches the defaults).
7. Back in the Blueprint editor, select the InstancedStaticMesh component and click the "+" in the Details view to add a new instance to the defaults.
8. Note that the Actor details view also reflects the addition of the new instance for the Actor instance that's in the current level.
9. Back in the Blueprint editor again, click the "+" once more to add a 2nd instance to the defaults.
10. Now note that the Actor details view does not reflect the addition of the 2nd instance, and it now thinks that the value differs from the default value (indicated by the presence of the "reset to default" arrow icon).

Expected result: The Actor details view shows the 2nd instance and does not show the "reset to default" arrow icon.