Until now, when viewing partial feedback in your Response Inbox, hidden variables and survey variables were not available. But now you can view hidden, survey and contact variables for Partial Responses, just as you can for completed responses.
This means you can also filter Partial Survey Responses by any variables.
This works with all of the methods of passing variables, including query strings, uploading CSV and sending emails or SMS or using Public APIs to send emails or SMS.
(This would be available only for Partial Responses submitted after June 30)