When the workflow start on item created, the task notification body email that has been configured to display Approval URL (via Nintex Live) is not generating a correct URL to the Nintex Live Task Form, instead it will generate this text {Common:TaskFormLiveURL}.  

Upgrade into Nintex Form 2013 version of 2.11.3.0 or hotfix version 2.11.2.21. 

This issue has been identified on the Nintex Form 2013 version 2.11.2.20 as a defect and has been fixed via a Hotfix on the Nintex Form 2013 version 2.11.2.21.