Custom Notification Not Available To Run

Trying to set up SMS notification using BurnsHA’s YouTube (https://www.youtube.com/watch?v=2oWe3UnZQo4) but when I try to run my test script to execute my sms_alert notification, I get an error stating that HA can’t find notify/sms_alert. My configuration.yaml looks like this:

# Notify
notify:
  - platform: smtp
    name: sms_alert
    server: smtp.gmail.com
    port: 587
    sender: [email protected]
    starttls: 1
    username: [email protected]
    password: my_password
    recipient: [email protected]

My script looks like this:

send_sms_alert: 
  alias: Test Notification
  sequence:
    - service: notify.sms_alert
      data:
        message: 'This is a test sms message!'

My configuration has passed homeassistant check. When I look at the available services, all I see is notify.notify, no notify.sms_alert. What am I doing wrong?

Not sure what happened over the last day as I have not made changes to my configuration, but all of a sudden, this evening I can now see the service notify.sms_alert. In looking through my home-assistant.log file, it looks like Hass.io on a RP3 might not install the smtp component until it is actually needed. My logs indicates that python updated some files and added smtp, without me directing this process. Perhaps someone else can explain this odd behavior more eloquently, but all is now working and all it took was some time for Hass.io magic to work its wonder… Not an answer I like or one that makes me comfortable with the quirks of HA. Perhaps a reboot of Hass.io instead of a restart of HA would have caused the needed smtp package to load.