重新部署堆栈时，ManagedPolicy不更新

Question

我在SAM模板yaml中的AWS::IAM::ManagedPolicy上附加了一个自定义AWS::Serverless::Function。托管策略具有通过参数!Sub允许使用的资源。当我在更改参数值后重新部署此堆栈时，它实际上并没有更新更改集中的托管策略。有什么想法吗？

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31 # allows for AWS SAM defined objects
Description: Serverless for Data Science Platform

Parameters:
  MyLambdaParam:
    Type: String
    Default: "sagemaker-endpoint-name"
    Description: SageMaker endpoint's name

...

  MyLambdaFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: mylambda/
      Handler: app.lambda_handler
      Runtime: python3.7
      FunctionName: !Sub "${AWS::StackName}-ODSP"
      Description: Transforms input and passes along to SageMaker for MyLambda
      Policies:
        - KMSDecryptPolicy:
            KeyId: !Ref KMSKeyId
        - !Ref SageMakerInvokeEndpointPolicy

...

  SageMakerInvokeEndpointPolicy:
    Type: AWS::IAM::ManagedPolicy
    Properties:
      PolicyDocument:
        Version: '2012-10-17'
        Statement:
          -   Effect: "Allow"
              Action:
                - "sagemaker:InvokeEndpoint"
              Resource: 
                - !Sub "arn:aws:sagemaker:${AWS::Region}:${AWS::AccountId}:endpoint/${MyLambdaParam}"