Reindexing Api is not copying the data

Using multi-node Elasticsearch version 7.14
I am facing an issue while doing reindexing.I want reindex all the indices given below

health status index                            uuid                   pri rep docs.count docs.deleted store.size pri.store.size
green  open   log-wlb-sysmon-2021.09.29-000014 gh4KHV6xRgSbk33Yk2cxJw   1   0          0            0       208b           208b
green  open   log-wlb-sysmon-2021.08.16-000015 EtF6odgpQGGRjQ0Nywqtxg   1   1  102154111            0    102.2gb         51.1gb
green  open   log-wlb-sysmon-2021.09.23-000019 tevWknvdRY-XwrEARoNY9g   1   1   32029659        89209     38.6gb         19.3gb
green  open   log-wlb-sysmon-2021.07.28-000013 6as7-RLlQpest5UkDIp5Rg   1   1   85912426        23421      100gb           50gb
green  open   log-wlb-sysmon-2021.08.27-000017 hAGeCkqhRlCBvmwBLonjaQ   1   1   93303600            0      102gb           51gb
green  open   log-wlb-sysmon-2021.08.19-000016 mkBAnhNMReyHzw0PJwkCHg   1   1   83527835            0      102gb           51gb
green  open   log-wlb-sysmon-2021.08.08-000014 ZxTk_TVRQiezNiggSQBejg   1   1   87312747            0    101.7gb         50.8gb
green  open   log-wlb-sysmon-2021.09.07-000018 HuDxDct7RGKOcuYFXCKA8w   1   1   92614553            0    101.6gb         50.8gb

How i done this is given below

1.

PUT %3Clog-wlb-sysmon-%7Bnow%2Fd%7D-000014%3E 
{
"aliases": {
   "log-wlb-sysmon": {
      "is_write_index": false      
   }
 },
 "settings": {
   "index.lifecycle.parse_origination_date":true
   , "refresh_interval": "-1"
   , "number_of_replicas": 0
 }
}

2.

POST _aliases
{
  "actions": [
    {
      "add": {
        "index": "log-wlb-sysmon-2021.09.23-000019",
        "alias": "log-wlb-sysmon",
        "is_write_index": false
      }
    }, {
      "add": {
        "index": "log-wlb-sysmon-2021.09.29-000014",
        "alias": "log-wlb-sysmon",
        "is_write_index": true
      }
    }
  ]
}

3.

POST _reindex?max_docs=87312747&wait_for_completion=false
{
  "conflicts": "proceed"
  , "source": {
    "index": "log-wlb-sysmon-2021.08.08-000014"
    , "size": 5000
    
  }
  , "dest": {
    "index": "log-wlb-sysmon-2021.09.29-000014"
  }
}

I dont know why it is copying.The index size is 100gb.
i get the task id... but it's not shown in GET /_task API

Problem solved.Issue was in mapping

To know the reason why it stopped.Run the following query
GET /_tasks/task_id
The task_id is the id which we got in