We did find that we can increase the session timeout for the web page security validation in central management.  Doing this has stopped the form from dumping entered data every 20 minutes.  Still the auto save would be nice to have as well.

Hi Emily,

Is there any update on this solution ?

Regards

JK

I'm pleased to announce that in the March 2017 builds of Nintex Forms 2013 & 2016, the Save and Continue feature has been introduced. This is a new button action that will allow users to save a form and keep the form open.

Release Notes:

Nintex Forms 2013 - Release Notes 

FYI Jared Purser‌, Emer McKenna‌, Jarrad Koppen‌

I was excited to read this only quickly to find out that this new feature is not available for O365 solution. Is there an alternative?

I just used rules to complete this action - have a checkbox that says I am ready to submit (thanks to my co-worker Catherine Norris) and using the checkbox checked in my rule I Save/Submit

Just to let you know, the Save and Submit button functionality was just released for O365!