Cannot find Alias field in Discover

Kibana version : 7.9

Elasticsearch version : 7.10

APM Server version : 7.10

APM Agent language and version : java 1.8

Fresh install or upgraded from other version? fresh install

I wanted to create field alias for a field in APM index pattern . I saw the field is created . But I am not able to see the field alias in Visualize/Discover. Is it an existing issue ?

I used the below to create alias

PUT apm-*/_mapping
{
  "properties": {
    "StoreNumber": {
      "type": "alias",
      "path": "labels.StoreNum"
    }
  }
}

Screen Shot showing the alias is created. I refreshed the indexes and still cant find it in discover

Anybody have any updates on this?