Nintex Workflow sends default SharePoint Task Notification instead of custom notification

My Nintex Workflow creates Nintex Workflow Tasks with Nintex Forms in a SharePoint 2016 subsite. Everything works as expected, except the task notification that is send to the user. I edited the task notification in the request approval action but SharePoint still sends the default task notification.

I even edited the notification templates on the website settings but SharePoint still sends the default e-mail.

Is there something that I am doing wrong?