The most common reason is because the Chameleon Shop View has been enabled for the survey, but the layout has no widgets added to it. 

Add widgets

The quickest way to add widgets is to select one of the "Presets" in the Chameleon Shop View Configurator.

Once you select the widget set, simply use the Save these settings button on the top right of the Configurator.

Turn CSV off

If you don't want to use the Chameleon Shop View, you can easily turn it off on the same screen by clicking the Turn Off Chameleon button at the top of the page.