Hi @angel.mendoza@daveramsey.com, welcome to the community!

Since you referenced a post that I answered in, thought I’d chime in.  As far as I know, you’re right and you can’t use a dynamic value from the event (e.g. event.list_key) as a value to update a property in the “Update Profile Property” action of a Flow.  Currently, it seems the property value can only be a hard-coded literal.

However - assuming you are sending events via the Javascript Client Library, one possible work around for you is to follow up with your Track Event to use the Identify API, given that you have access to the email address (or ID) at the time of the event, to pass in the properties you want to append to that profile’s custom property (e.g. list_key) at the same time you pass in the Event/Metric. 

See the example in the API Docs:

<script>
  var _learnq = _learnq || n];

  // Identifying a person and tracking special Klaviyo properties.
  _learnq.push(>'identify', {
    '$email' : 'thomas.jefferson@example.com',
    '$first_name' : 'Thomas',
    '$last_name' : 'Jefferson'
  }]);

  // Adding custom properties. Note that Klaviyo understands different data types.
  _learnq.push(>'identify', {
    'Plan' : 'Free Trial',
    'SignUpDate' : '2016-01-27 12:10:05',
    'HasFilledOutProfile' : false
  }]);
</script>

In this example, they are also adding custom properties like “Plan, SignUpDate, and HasFilledOutProfile” with their respective values.  

If you are sending “Track Events” via the Server Side Library, then you can just add those properties along with the Server Side track event.
See this example: 

{
  "token": "PUBLIC_KEY",
  "event": "Ordered Product",
  "customer_properties": {
    "$email": "bob@klaviyo.com",
    "pet-type":"Dog"
  },
  "properties": {
    "item_name": "Dog Collar",
    "$value": 15
}

In this example, they are adding a custom profile property “pet-type” with the value “Dog” to be part of the Profile at the time of the event/metric being passed in.

Hope this helps!

@retention - Thanks for your prompt response

Using the APIs is what I am trying to avoid. I want to transfer the responsibility of managing “profile properties” to my Marketing Team. Basically, I use the API to publish events with properties and they take it from there.

It feels “natural” or “intuitive” to allow for a “profile property update” based on the value of an event variable/property

Hi team, we occurred the same issue and hope that after 3 years, we’re now able to update profile property (using profile property update in flow) to update a variable in a metric/ event, aren’t we? Please support to confirm. Thank you so much!