I did these in the code and rebuilt my Blueprint
header:
UPROPERTY(EditAnywhere, BluePrintReadWrite)
UStaticMeshComponent* mesh;
UPROPERTY()
USceneComponent* root;
source
mesh = CreateDefaultSubobject<UStaticMeshComponent>("mesh");
root = CreateDefaultSubobject<USceneComponent>(TEXT("root"));
RootComponent = root;
mesh->AttachTo(root);