Webhook based on JQL would not trigger when used in Workflow Post Functions

Steps to Reproduce:

1. Create a Project Management project for the test named PM for example.
2. Create another Administrator user called "Admin"
3. Create a webhook and set the JQL:

   project = PM AND assignee = admin

4. Navigate to JIRA Administration > Issues > Workflow
5. Edit "PM: Project Management Workflow"
6. Change to "Text" view and click on "Start Progress"
7. Move to "Post Function" tab and make sure the post function below exist:

   Assign the issue to the current user. Please note that the issue will only be assigned to the current user if the current user has the 'Assignable User' permission.

8. Add another post function and choose "Trigger a Webhook" to select the previous webhook.
9. Move it to the bottom in order to make it the last to be triggered and publish the workflow.
10. Login as "admin", create an issue in PM project and click the "Start Progress" button transition.

Expected Result:

With the ticket is updated its assignee to the user that triggered the transition and re-indexed, the webhook will be triggered in the last with the issue met the JQL requirement.

Actual Result:

The webhook is not triggered.

Notes:

Webhook will be the example for the behavior, another case will be Hipchat ticket linked below. It appears to me that the change is only happening after all the last Post Function rule. With the result where the Webhook is not triggered, it means that the Post Function Rule did not run independently as the Webhook Rule did not catch the change of the assignee. The database changes will happen after all the rule triggered it seems.