Data only blueprints that are explicitly flagged for nativization do not nativize. (Makes sense that they don't when they're not explicitly told, but if someone goes out of the way to flag them to, we probably should.)
Found on //UE4/Release-4.15 CL-3269047
Result: Even though we flagged the child, data-only, blueprint for nativization, it was not nativized and is still present in the blueprints folder.
Expected: Child blueprint asset is not in the blueprint folder, as it's been nativized.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-41070 in the post.