I created a function to default the value of a custom field in the task module based on the related lead. I marked to execute whenever a task is created or edited. It only runs when editing but not when creating? Is this a bug or something missing?

Created in Automation | Actions | Custom Functions and defining taskId argument as Task.TaskId and leadId as Lead/ Propsect.Lead/ProspectId.

Any thoughts on why this doesn't fire on create?