Hey Ryan,

could you describe what the maximize button should do?

In general, Nintex' uservoice space is always a good point for requesting features:

Customer Feedback for Nintex 

Kind regards,

Enrico

Open in Dialog box SharePoint 2010

Open in Dialog box SharePoint 2013

Maximize/Minimize button shown in the SharePoint 2010 picture.

Has this feature been removed?

Can we add it back?

Ah now I see what you mean. Well no, it hasn't been removed. In fact the maximize button was part of SharePoint 2010's modal dialog framework which has been changed in 2013/2016. So the functionality wasn't a Nintex functionality but one of SharePoint.

If you need full screen display though you can disable dialogs on each list in the lists settings. This will open the form in full screen. Would this be an alternative?

Kind regards,

Enrico

Oh that's interesting I had always thought it was Nintex. Unfortunately we have to have those forms in dialog. Do you know if it's possible to modify the SharePoint framework to show that?

I'm afraid I don't know how to modify the dialog framework and personally I wouldn't manipulate it. If you could describe your scenario people might have other ideas about how to achieve your goal. Whats the main reason why you need the ability to maximize your modal dialogs?