Unreal Engine中BTService无法更新Blackboard Key值问题

问题背景 #

我正在为游戏中的AI敌人开发低血量“撤退”逻辑，为此创建了一个BTService，用于实时获取角色Health值并存储到Blackboard Key中。
目前遇到异常：该服务仅能首次正确设置“Health”值，后续不再更新，即使敌人血量下降，Blackboard Key仍固定为初始值不变。

已知现象 #

• ShooterCharacter类中定义有Health变量
• 对应AI的行为树中设有同名“Health” Blackboard Key，用于存储ShooterCharacter类的Health值
• 为实现值同步逻辑，开发了名为“Update Character Health”的BTService
• 游戏启动时该服务运行符合预期，行为树中Health键值正确显示为ShooterCharacter的初始血量70
• 后续服务停止生效，即使对应ShooterCharacter实例的血量降至40，键值仍停留在70

相关实现代码 #

BTService_CharacterHealth.h #

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "BehaviorTree/Services/BTService_BlackboardBase.h"
#include "BTService_CharacterHealth.generated.h"

/**
 * s
 */
UCLASS()
class SIMPLESHOOTER_API UBTService_CharacterHealth : public UBTService_BlackboardBase
{
    GENERATED_BODY()

public: 
    UBTService_CharacterHealth();

protected: 
    virtual void TickNode(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, float DeltaSeconds) override;   
};

BTService_CharacterHealth.cpp #

// Fill out your copyright notice in the Description page of Project Settings.


#include "BTService_CharacterHealth.h"
#include "AIController.h"
#include "BehaviorTree/BlackboardComponent.h"
#include "GameFramework/Pawn.h"
#include "Kismet/GameplayStatics.h"
#include "ShooterCharacter.h"

UBTService_CharacterHealth::UBTService_CharacterHealth()
{
    NodeName = "Update Character Health";
}

void UBTService_CharacterHealth::TickNode(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, float DeltaSeconds)
{
    Super::TickNode(OwnerComp, NodeMemory, DeltaSeconds);

    AShooterCharacter*  Character = Cast<AShooterCharacter>(OwnerComp.GetAIOwner()->GetPawn());

    if (Character == nullptr)
    {
        return;
    }

    OwnerComp.GetBlackboardComponent()->SetValueAsFloat(GetSelectedBlackboardKey(), Character->Health);
};

排查进展 #

我最初怀疑问题与OwnerComp.GetBlackboardComponent()->SetValueAsFloat(GetSelectedBlackboardKey(), Character->Health);语句相关，于是在AShooterCharacter* Character = Cast<AShooterCharacter>(OwnerComp.GetAIOwner()->GetPawn());语句后添加了如下日志：

UE_LOG(LogTemp, Warning, TEXT("Character Health: %f"), Character->Health);

日志可正常实时输出最新血量值，当角色血量为40时会正确打印40，但即使日志正常输出，Blackboard Key的值仍停留在70不变。目前暂未定位到该问题的根因，可按需补充其他相关信息。

内容的提问来源于stack exchange，提问作者jovandl