AWS API Gateway: Unable to enable CORS for some resources defined in OpenAPI Specification v.3

I am using OpenAPI Specification 3 with terraform to create resources and methods in my API Gateway. Surprisingly for some resources CORS is not getting enabled. I am not seeing any pattern for which it is failing. For enablement of CORS, I am using the standard way of using the OPTIONS method provided by Amazon documentation. Here is the code for the OPTIONS method:

options: summary: CORS support description: Enable CORS by returning correct headers tags: - CORS responses: 200: description: Default response for CORS method headers: Access-Control-Allow-Origin: schema: type: string Access-Control-Allow-Methods: schema: type: string Access-Control-Allow-Headers: schema: type: string content: {} x-amazon-apigateway-integration: type: mock requestTemplates: application/json: { "statusCode" : 200 } responses: default: statusCode: 200 responseParameters: method.response.header.Access-Control-Allow-Headers: "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token'" method.response.header.Access-Control-Allow-Methods: "'DELETE,GET,HEAD,OPTIONS,PATCH,POST,PUT'" method.response.header.Access-Control-Allow-Origin: "'*'" responseTemplates: application/json: {}

On investigating and troubleshooting through the API Gateway Console, I observed that in Integration Request, request template this line is not getting implemented: { "statusCode" : 200 } because of which I am getting the following error on testing Options method from API Gateway Console: *Thu Jun 22 02:23:16 UTC 2023 : Execution failed due to configuration error: Unable to parse statusCode. It should be an integer that is defined in the request template. Thu Jun 22 02:23:16 UTC 2023 : Method completed with status: 500 This results in a CORS issue when a GET method is called attached with the same resource. I am not sure why it is failing to implement because same OPTIONS method is implemented for other resources and they are working fine.