I created a simple custom action with Nintex 2013 template and I deployed in a SharePoint 2016 server.
After the deployment the action is visible in the side panel in the Nintex workflow designer but when I drag and drop the action in the designer nothing happens, the action doesn't appear in the workflow. In the console appears the following error each time I tryed to drag and drop the action in the designer:
The error appears with several browsers (IE 11, Chrome).
What does the error mean?
The action is enabled in the actions list and it is configured as follow: 
