服务器多播函数，客户端未得到响应。

您好，感谢您的回答，但是我提供的代码里构造函数已经标记为可复制。所以可能的问题是您所说的指针为空？
除了使用多播函数，我所能想到的就是属性同步。所以我做了如下更改。

UCLASS()
class MYPROJECT_API ATargetCube : public AActor
{
	GENERATED_BODY()
	
public:	

	ATargetCube();

	virtual void GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const override;
	
protected:

	virtual void BeginPlay() override;

private:

	UPROPERTY(EditDefaultsOnly)
	UBoxComponent* BoxComponent;

	UPROPERTY(EditDefaultsOnly)
	UStaticMeshComponent* BoxMesh;

	UPROPERTY(EditDefaultsOnly)
	UMaterialInstance* DoublePointsCubeMaterial;

	UPROPERTY(ReplicatedUsing = "OnRep_UseDoublePointsCubeMaterial")
	bool bUseDoublePointsCubeMaterial = false;

	UFUNCTION()
	void OnRep_UseDoublePointsCubeMaterial();
};

CPP文件是：

ATargetCube::ATargetCube()
{
	PrimaryActorTick.bCanEverTick = false;
	bReplicates = true;

	BoxComponent = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxComponent"));
	BoxComponent->SetBoxExtent(FVector(50.f, 50.f, 50.f));
	SetRootComponent(BoxComponent);

	BoxMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("BoxMesh"));
	BoxMesh->SetupAttachment(GetRootComponent());
}

void ATargetCube::BeginPlay()
{
	Super::BeginPlay();
	if (AMyProjectGameMode* GameMode = Cast<AMyProjectGameMode>(UGameplayStatics::GetGameMode(this)))
	{
		Score = GameMode->GetCubeScore();
		if (GameMode->MustSpawnDoublePointsCube() || (GameMode->CanSpawnDoublePointsCube() && FMath::RandBool()))
		{
			GameMode->AddDoublePointsCubeCount();
			bUseDoublePointsCubeMaterial = true;
			BoxMesh->SetMaterial(0, DoublePointsCubeMaterial);
		}
		GameMode->AddCubeCount();
	}
	else if (bUseDoublePointsCubeMaterial)
	{
		BoxMesh->SetMaterial(0, DoublePointsCubeMaterial);
	}
}

void ATargetCube::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
{
	Super::GetLifetimeReplicatedProps(OutLifetimeProps);

	DOREPLIFETIME(ThisClass, bUseDoublePointsCubeMaterial);
}

void ATargetCube::OnRep_UseDoublePointsCubeMaterial()
{
	bUseDoublePointsCubeMaterial = true;
	BoxMesh->SetMaterial(0, DoublePointsCubeMaterial);
}

通过这种方式成功实现了我的需求。