The error "Unable to list buckets in the selected region. Please ensure buckets are available in the selected region and try again." typically occurs when required IAM permissions are missing, even if the buckets are available in the specified region.

1. Identify Missing Permissions

1.  Investigate the error and check the IAM policy for the required permissions. In this case, the `GetBucketLocation` permission was missing.

2. Update IAM Policy

1. Add the required permission `s3:GetBucketLocation` to the IAM policy. Additionally, ensure that the following permissions are available for adding non-immutable buckets:
   

        - `s3:ListAllMyBuckets`

        - `s3:ListBucket`

        - `s3:PutObject`

        - `s3:PutObjectAcl`

        - `s3:PutObjectTagging`

        - `s3:PutObjectVersionTagging`

        - `s3:PutObjectVersionAcl`

        - `s3:DeleteObject`

        - `s3:DeleteObjectVersion`

        - `s3:GetObject`

        - `s3:GetObjectAcl`

        - `s3:GetObjectTagging`

        - `s3:GetObjectVersion`

        - `s3:GetBucketLocation`

        - `s3:ListBucketMultipartUploads`

        - `s3:ListMultipartUploadParts`

        - `s3:AbortMultipartUpload`

        - `s3:ListBucketVersions`

3. Verify Object Repository Creation

1. After updating the IAM policy, attempt to add the object repository again. The process should complete successfully if all required permissions are correctly configured.
   

By updating the IAM policy with the necessary permissions, you can resolve the error and successfully manage your S3 buckets.