Unable to copy elasticache for redis backup to S3 bucket in the same region

Hi, I need to export a backup of Elasticache for redis to a S3 bucket which has the bucket policy according to the document at https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/backups-exporting.html. And my IAM has full access to the S3 resources.

When I use CLI command 'aws elasticache copy-snapshot --source-snapshot-name <source snapshot name> --target-snapshot-name <target snapshot name> --target-bucket <S3 bucket name>, I got some normal output data without error message. However, I don't see any files in the S3 bucket I created earlier. The same issue when I used the Elasticache console to copy the backup to the S3 bucket.

Here're some properties of the redis cluster:

• Node type: cache.t2.micro
• Engine version: 5.0.6
• Cluster mode: off

Bucket policy: { "Version": "2012-10-17", "Statement": [ { "Sid": "ElastiCacheRedisBackupAccess", "Effect": "Allow", "Principal": { "Service": "ap-southeast-1.elasticache-snapshot.amazonaws.com" }, "Action": [ "s3:PutObject", "s3:GetObject", "s3:ListBucket", "s3:GetBucketAcl", "s3:ListMultipartUploadParts", "s3:ListBucketMultipartUploads" ], "Resource": [ "arn:aws:s3:::<S3 bucket name>", "arn:aws:s3:::<S3 bucket name>/*" ] } ] }

Any idea why I don't see the files in the S3 bucket? Thanks!