How to solve problem of TSoftObjectPtr Get() asset fail in packaged build?

I have a TSoftObjectPtr UIBlueprint property.

It refers to the asset:


However when I load the asset by UIBlueprint.Get(), called during BeginPlay() of an actor component.
it only works in Editor, returning a valid UBlueprint* pointer.
But it always fails in packaged build, returning a nullptr.
How to solve it?

update: I’ve tried following the approach in Unreal Doc: Referencing Assets | Unreal Engine, using codes as:

    UPROPERTY(EditDefaultsOnly, BlueprintReadWrite, Category=Building)
    TSoftObjectPtr<UStaticMesh> BaseMesh;
    UStaticMesh* GetLazyLoadedMesh()
        if (BaseMesh.IsPending())
            const FSoftObjectPath& AssetRef = BaseMesh.ToStringReference();
            BaseMesh = Cast< UStaticMesh>(Streamable.SynchronousLoad(AssetRef));
        return BaseMesh.Get();

But still, the asset is only loaded successfully in editor play. While fails by just returning a nullptr in packaged game play.

I double this question! Been onto it since 4.16, but no luck on how async load should work with c++ yet