Tagged OpenSearch Serverless Resources Not Appearing in AWS Cost Explorer

There are several potential reasons why your tagged OpenSearch Serverless resources are not appearing in the Tagged Resources section of AWS Cost Explorer. Here are some steps you can take to troubleshoot and resolve this issue:

1. Activate cost allocation tags: Even if you've applied tags to your resources, they need to be activated for cost allocation purposes. Sign in to the AWS Billing and Cost Management console, navigate to the Cost Allocation Tags section, and ensure that the tags you've applied to your OpenSearch Serverless resources are activated. This activation process can take up to 24 hours to complete.

2. Wait for tag data to appear: After activating the cost allocation tags, it may take up to 24 hours for the tag data to appear in Cost Explorer. Be patient and check again after a full day has passed.

3. Verify resource charges: Cost Explorer only displays tags for resources that have actually incurred charges. Make sure your OpenSearch Serverless resources have generated costs before expecting to see them in the Tagged Resources section.

4. Check tag key case sensitivity: AWS treats tag keys as case-sensitive. Ensure that the tag keys you're looking for in Cost Explorer exactly match the activated tag keys, including the correct capitalization.

5. Confirm tag application: Double-check that the tags are correctly applied to all relevant resources. If some resources are missing the tags, their costs won't be included in the Tagged Resources section.

6. Account permissions: If you're using AWS Organizations, make sure you have the necessary permissions to access Cost Explorer and view tagged resources. You may need to contact your management account to grant the required access.

7. Recent account changes: If your account has recently moved between different AWS Organizations, your active tags may have been deactivated. In this case, they would need to be reactivated by the new management account.

If you've followed these steps and are still unable to see your tagged OpenSearch Serverless resources in Cost Explorer, it may be worth contacting AWS support for further assistance. They can provide more specific guidance based on your account configuration and resource setup.
Sources
Activate cost allocation tags associated with the solution - Migration Assistant for Amazon OpenSearch Service
What are the reasons for Budget not working using cost filter with specific tags even after activating these tags in Cost Allocation Tags section ? | AWS re:Post