AWS::ApplicationAutoScaling::ScalableTarget是用来自动扩展AWS资源的服务。对于Lambda ProvisionedConcurrency的工作不如预期，可能是配置有误或者缺少必要的配置。以下是一个解决方法的示例代码：

首先，确保已经创建了Lambda函数，并配置了ProvisionedConcurrency。然后，创建一个ScalableTarget并将其与Lambda函数关联起来，在创建ScalableTarget时，需要提供Lambda函数的ARN以及其他必要的配置。

Resources:
  MyLambdaFunction:
    Type: AWS::Lambda::Function
    Properties:
      # Lambda函数的配置

  MyScalableTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Properties:
      MaxCapacity: 10
      MinCapacity: 1
      ResourceId: !Sub function:${MyLambdaFunction.Arn}
      RoleARN: !GetAtt MyScalableTargetRole.Arn
      ScalableDimension: "lambda:function:ProvisionedConcurrency"
      ServiceNamespace: "lambda"

  MyScalableTargetRole:
    Type: AWS::IAM::Role
    Properties:
      # ScalableTarget所需的IAM角色配置

  MyScalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Properties:
      PolicyName: MyScalingPolicy
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref MyScalableTarget
      TargetTrackingScalingPolicyConfiguration:
        TargetValue: 0.5
        ScaleInCooldown: 60
        ScaleOutCooldown: 60
        PredefinedMetricSpecification:
          PredefinedMetricType: LambdaProvisionedConcurrencyUtilization

  MyAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmName: MyAlarm
      AlarmDescription: "Alarm for MyScalingPolicy"
      AlarmActions:
        - !Ref MyScalingPolicy
      ComparisonOperator: GreaterThanOrEqualToThreshold
      EvaluationPeriods: 1
      MetricName: LambdaProvisionedConcurrencyUtilization
      Namespace: AWS/Lambda
      Period: 60
      Statistic: Average
      Threshold: 80
      TreatMissingData: breaching
      Dimensions:
        - Name: FunctionName
          Value: !GetAtt MyLambdaFunction.FunctionName

上述代码中，创建了一个ScalableTarget和ScalingPolicy，以及一个CloudWatch Alarm用于监控Lambda函数的ProvisionedConcurrency利用率。根据具体的需求，可以调整MaxCapacity、MinCapacity、TargetValue和Threshold等参数。

通过以上代码示例，可以解决AWS::ApplicationAutoScaling::ScalableTarget对于Lambda ProvisionedConcurrency的工作不如预期的问题。