Data field type changed from date to text

Elastic Stack Elasticsearch
1

My logstash configuration file like this

After reading the csv file I change the log_datetime field from "dd-MM HH:mm:ss" to "2024-05-23T01:18:07.000Z"
by the following configuration in test.conf

date {
      match => [ "log_datetime", "dd-MM HH:mm:ss" ]
      timezone => "America/New_York"
      target => "log_datetime"
}

However, I find in my elasticsearch the log_datetime changed to text format.

log_datetime

With the similar configuration file in logstash.
For another source server it works fine. Any idea?

2
  1. I stop the filebeat service in the source server
  2. remove the index in Elasticsearch
  3. Move all logs in the source server's folder (folderA) to different folder (folderB)
  4. Start the filebeat service in the source server
  5. Copy log files from folderB to folderA in batch, each batch 10 files
  6. finally everything works ..i.e. the data type keep.....date formate

Actually I don't know why? Any idea?