InvalidArn error specific to StepFunctionsLocal - not reproducible in 'live' AWS stepfunctions

Minimum reproduction:

Create a state machine, with a singular step with resource arn:aws:states:::states:startExecution.sync, i.e. executing another state machine, and define the arn using Fn::GetAtt function.

When executing the parent state machine in Step Functions Local:

Invalid Arn: '{"Fn::GetAtt":["ChildStateMachineId","Arn"]}' (Service: AWSStepFunctions; Status Code: 400; Error Code: InvalidArn; Request ID: null; Proxy: null)

What happens when exeucuting the parent in 'live' AWS stepfunctions console:

ExecutionSucceeded

Template for an example state machine to reproduce (in yml for brevity):

AWSTemplateFormatVersion: 2010-09-09
Description: The AWS CloudFormation template for this Serverless application
Resources:
  ServerlessDeploymentBucket:
    Type: 'AWS::S3::Bucket'
    Properties:
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256
  ServerlessDeploymentBucketPolicy:
    Type: 'AWS::S3::BucketPolicy'
    Properties:
      Bucket: !Ref ServerlessDeploymentBucket
      PolicyDocument:
        Statement:
          - Action: 's3:*'
            Effect: Deny
            Principal: '*'
            Resource:
              - !Join 
                - ''
                - - 'arn:'
                  - !Ref 'AWS::Partition'
                  - ':s3:::'
                  - !Ref ServerlessDeploymentBucket
                  - /*
              - !Join 
                - ''
                - - 'arn:'
                  - !Ref 'AWS::Partition'
                  - ':s3:::'
                  - !Ref ServerlessDeploymentBucket
            Condition:
              Bool:
                'aws:SecureTransport': false
  ParentStateMachineIdRole:
    Type: 'AWS::IAM::Role'
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service: !Sub 'states.${AWS::Region}.amazonaws.com'
            Action: 'sts:AssumeRole'
      Policies:
        - PolicyName: dev-stepfunctions-statemachine
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Effect: Allow
                Action:
                  - 'states:StartExecution'
                Resource:
                  - !GetAtt 
                    - ChildStateMachineId
                    - Arn
              - Effect: Allow
                Action:
                  - 'states:DescribeExecution'
                  - 'states:StopExecution'
                Resource: '*'
              - Effect: Allow
                Action:
                  - 'events:PutTargets'
                  - 'events:PutRule'
                  - 'events:DescribeRule'
                Resource:
                  - !Sub 
                    - >-
                      arn:${AWS::Partition}:events:${AWS::Region}:${AWS::AccountId}:rule/StepFunctionsGetEventsForStepFunctionsExecutionRule
                    - {}
  ChildStateMachineIdRole:
    Type: 'AWS::IAM::Role'
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service: !Sub 'states.${AWS::Region}.amazonaws.com'
            Action: 'sts:AssumeRole'
      Policies:
        - PolicyName: dev-stepfunctions-statemachine
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Effect: Deny
                Action: '*'
                Resource: '*'
  ParentStateMachineId:
    Type: 'AWS::StepFunctions::StateMachine'
    Properties:
      DefinitionString: !Sub 
        - |-
          {
            "StartAt": "StartChildStateMachine",
            "States": {
              "StartChildStateMachine": {
                "Type": "Task",
                "Resource": "arn:aws:states:::states:startExecution.sync",
                "Parameters": {
                  "StateMachineArn": "${1e6e8813e9805d9988de892f7ee7123c}",
                  "Input": {
                    "NeedCallback": false
                  }
                },
                "End": true,
                "ResultPath": "$.StartChildStateMachine"
              }
            }
          }
        - 1e6e8813e9805d9988de892f7ee7123c: !GetAtt 
            - ChildStateMachineId
            - Arn
      RoleArn: !GetAtt 
        - ParentStateMachineIdRole
        - Arn
      StateMachineName: ParentStateMachine
    DependsOn:
      - ParentStateMachineIdRole
  ChildStateMachineId:
    Type: 'AWS::StepFunctions::StateMachine'
    Properties:
      DefinitionString: |-
        {
          "StartAt": "ChildDone",
          "States": {
            "ChildDone": {
              "Type": "Succeed"
            }
          }
        }
      RoleArn: !GetAtt 
        - ChildStateMachineIdRole
        - Arn
      StateMachineName: ChildStateMachine
    DependsOn:
      - ChildStateMachineIdRole
Outputs:
  ServerlessDeploymentBucketName:
    Value: !Ref ServerlessDeploymentBucket
    Export:
      Name: sls-stepfunctions-dev-ServerlessDeploymentBucketName
  ParentStateMachineIdArn:
    Description: Current StateMachine Arn
    Value: !Ref ParentStateMachineId
    Export:
      Name: sls-stepfunctions-dev-ParentStateMachineIdArn
  ChildStateMachineIdArn:
    Description: Current StateMachine Arn
    Value: !Ref ChildStateMachineId
    Export:
      Name: sls-stepfunctions-dev-ChildStateMachineIdArn

Output of aws stepfunctions --endpoint http: //localhost:8083 describe-state-machine --state-machine-arn arn:aws:states:eu-north-1:101010101010:stateMachine:ParentStateMachine

{
    "stateMachineArn": "arn:aws:states:eu-north-1:101010101010:stateMachine:ParentStateMachine",
    "name": "ParentStateMachine",
    "status": "ACTIVE",
    "definition": "{\"StartAt\":\"StartChildStateMachine\",\"States\":{\"StartChildStateMachine\":{\"Type\":\"Task\",\"Resource\":\"arn:aws:states:::states:startExecution.sync\",\"Parameters\":{\"StateMachineArn\":{\"Fn::GetAtt\":[\"ChildStateMachineId\",\"Arn\"]},\"Input\":{\"NeedCallback\":false}},\"End\":true,\"ResultPath\":\"$.StartChildStateMachine\"}}}",
    "roleArn": "arn:aws:iam::101010101010:role/DummyRole",
    "type": "STANDARD",
    "creationDate": "2023-09-18T14:09:40.648000+02:00"
}