Ignore_case doesn't work for elastic search stop token filter

[taugusti (Anthony August)]

Trying to follow the example from the URL below to ignore case for stop words. However it doesn't seem to stop case insensitive stop words. for eg it stop "the", but not "The"

Stop token filter | Elasticsearch Guide [7.17] | Elastic

PUT /my-index-000001
{
  "settings": {
    "analysis": {
      "analyzer": {
        "default": {
          "tokenizer": "whitespace",
          "filter": [ "my_custom_stop_words_filter" ]
        }
      },
      "filter": {
        "my_custom_stop_words_filter": {
          "type": "stop",
          "ignore_case": true
        }
      }
    }
  }
}

Then I do

GET my-index-000001/_analyze
{
  "field": "ASCII_FIELD", 
  "text" :"this that a b The is IS was açaí à la carte"
}

However I see "The" and "IS" are tokens
Then add a document

PUT my-index-000001/_doc/1
{

  "ASCII_FIELD" :"this that a b The is IS was  açaí à la carte"
}

and when I search like this, I shouldn't get a result, but I'm getting

GET my-index-000001/_search
{
  "query": {
    "match": {
      "ASCII_FIELD": "The"
    }
  }
}