Tts.google_say skips the hour

1

using this script:

  googlehome_announce:
    alias: 'Googlehome announce'
    sequence:
      - service: tts.google_say
        data_template:
          language: en
          entity_id: media_player.googlehome_woonkamer, media_player.googlehome_hobbykamer
          message: >
            {% set name = states[entityid.split('.')[0]][entityid.split('.')[1]].name %}
            {{as_timestamp(now()) | timestamp_custom('%X') }} :
            {% if tostate == 'not_home' %}
              {{-name }} left {{fromstate}}
            {% elif fromstate == 'not_home' %}
              {{-name }} arrived at {{tostate}}
            {% else %}
              {{-name }} left {{fromstate}} and arrived at {{tostate}}
            {% endif %}

my presence tracking is announced over my google homes perfectly, with one issue: it skips the hour. The time is registered perfectly, which I can check using this almost same script:

  notify_presence:
    alias: 'Notify presence'
    sequence:
      - service: notify.notify
        data_template:
          title: >
            {{trigger}}: {{ states[entityid.split('.')[0]][entityid.split('.')[1]].name }} notification
          message: >
            {% set name = states[entityid.split('.')[0]][entityid.split('.')[1]].name %}
            {{as_timestamp(now()) | timestamp_custom('%X') }} :
            {% if tostate == 'not_home' %}
              {{-name }} left {{fromstate}}
            {% elif fromstate == 'not_home' %}
              {{-name }} arrived at {{tostate}}
            {% else %}
              {{-name }} left {{fromstate}} and arrived at {{tostate}}
            {% endif %}

showing me the exact message in a notification.
any thoughts on why this would happen? Could it be some kind of lag?

changing to:

              Hi, at {{as_timestamp(now()) | timestamp_custom('%X') }} :

solves the issue for me, but still would be interested why this happens.