AWS Redshift UNLOAD not firing S3 PUT event
You did not tell how big data amounts you tested with, but if you test ok with little data block successfully and larger real situation fails, there may occur same as occurred here:


  The larger files are almost certainly being uploaded via S3 Multipart Upload instead of a regular Put operation.
  
  ..
  
  It sounds like the function is only subscribed to s3:ObjectCreated:Put events currently, and you need to add s3:ObjectCreated:CompleteMultipartUpload to the configuration.