Store secrets in keystore using ansible

Hello,

I would like to store AWS credentials in the keystore.
To deploy elasticsearch I used the official ansible playbook.
Following the documentation I prepared this test node configuration:

    - hosts: 192.168.172.11
      roles:
        - role: elastic.elasticsearch
      vars:
        es_api_host: 192.168.172.11
        es_heap_size: "8g"
        es_data_dirs:
          - "/elasticsearch/data"
        es_log_dir: "/elasticsearch/logs"
        es_config:
          node.name: "elastic01"
          cluster.name: "name"
          cluster.initial_master_nodes: "192.168.172.11"
          discovery.seed_hosts: "192.168.172.11:9300"
          http.port: 9200
          network.host: 192.168.172.11
          node.data: true
          node.master: true
          bootstrap.memory_lock: false
        es_plugins:
          - plugin: ingest-attachment
          - plugin: repository-s3
        es_keystore_entries:
          - key: s3.client.default.access_key
            value: access_key
            state: present
          - key: s3.client.default.secret_key
            value: secret_key
            state: present

but after the playbook run I found only this in the keystore:

    ./elasticsearch-keystore list -v
    keystore.seed

How to troubleshoot this issue ?

Thanks a lot.