Error creating SNS integration in ApiGateway

Serverless Framework
,
1

I have an AWS serverless recipe that is working fine except for creating A POST method to hook straight to SNS, which is possible via the console. The relevant resource definition is

    GatewayResourceApiPost:
      Type: AWS::ApiGateway::Method
      Properties:
        HttpMethod: POST
        ResourceId: !Ref GatewayResourceApi
        RestApiId: !Ref Gateway
        ApiKeyRequired: false
        AuthorizationType: "NONE"
        Integration:
          RequestParameters:
            integration.request.header.Content-Type: "application/x-www-form-urlencoded"
          IntegrationHttpMethod: POST
          Type: AWS
          Uri: "arn:aws:apigateway:${self:provider.region}:sns:action/Publish"
          Credentials: !Ref IamRoleGatewayExecution
          PassthroughBehavior: WHEN_NO_MATCH

sls deploy returns following error

An error occurred: GatewayResourceApiPost - Invalid ARN specified in the request (Service: AmazonApiGateway; Status Code: 400; Error Code: BadRequestException; Request ID: 4fa6a8ff-1128-4213-a774-d1bdfc66081e; Proxy: null)

The resultant cloudformation-template-update-stack.json contains the following resource section

    "GatewayResourceApiPost": {
      "Type": "AWS::ApiGateway::Method",
      "Properties": {
        "HttpMethod": "POST",
        "ResourceId": {
          "Ref": "GatewayResourceApi"
        },
        "RestApiId": {
          "Ref": "Gateway"
        },
        "ApiKeyRequired": false,
        "AuthorizationType": "NONE",
        "Integration": {
          "RequestParameters": {
            "integration.request.header.Content-Type": "application/x-www-form-urlencoded"
          },
          "IntegrationHttpMethod": "POST",
          "Type": "AWS",
          "Uri": "arn:aws:apigateway:eu-west-2:sns:action/Publish",
          "Credentials": {
            "Ref": "IamRoleGatewayExecution"
          },
          "PassthroughBehavior": "WHEN_NO_MATCH"
        }
      }
    },

If I remove the Integration part, the resource is created with no method as expected.

By way of comparison, I manually created the resource in the console, deployed to a stage and downloaded the definition.

openapi: "3.0.1"
info:
  title: "Gateway"
  version: "2020-12-29T08:27:11Z"
servers:
- url: "https://*********.execute-api.eu-west-2.amazonaws.com/{basePath}"
  variables:
    basePath:
      default: "/dev"
paths:
  /api:
    post:
      x-amazon-apigateway-integration:
        credentials: "arn:aws:iam::**********:role/gateway-cloud-poc-poc-IamRoleGatewayExecution-18ER9Q32F4YXN"
        uri: "arn:aws:apigateway:eu-west-2:sns:action/Publish"
        responses:
          default:
            statusCode: "200"
        passthroughBehavior: "when_no_match"
        httpMethod: "POST"
        type: "aws"
components: {}

Is this a known issue for serverless, or am I missing some secret sauce to make this work?

Any help appreciated.

sls --version
Framework Core: 1.83.2 (local)
Plugin: 3.8.4
SDK: 2.3.2
Components: 2.34.9