Index is not created inside the Amazon OpenSearch cluster

I am following the turorial "Build a Full Stack Large Language Model Powered Chatbot: Extract Insights from Unstructured Documents" at https://community.aws/tutorials/fullstack-llm-langchain-chatbot-on-aws. I have completed all steps up to step 5 but there I face the following problem: There is a Lambda function which is invoked by an S3 bucket event. The Lambda function initiates a Fargate task, which in turn runs a Docker container containing a python script, responsible for generating embeddings in Amazon OpenSearch under a new OpenSearch index. The problem is that the index is not created in the Amazon OpenSearch cluster as it should. Do you think it is a policy issue in the fargate task? I don't see any errors in CloudWatch from the Lambda Function. Could you please help me? Thank you for your time.