How to get the ID of item which is just created with Nintex call web service
When you use the standard create item in Nintex you have the option to store the new item ID in a variable, this option isn’t available when you create an item via web service.
The solution is to use the Store result in option in the Call web service action.
Now add the Query XML action and query the result from the web service with XPath (//@ows_ID)
This result will be your newly created item ID