"NO PREVIEW AVAILABLE" message for some widgets in Service Portal designer
No Preview Available - Service Portal desginer
Not all out-of-box widgets have the preview feature. The Service Portal form UI and Designer use the field "has_preview" which defines whether preview data is available for the widget. If the widget's has_preview field value is set to false, it indicates that there is no preview data available for that widget to be shown in the designer.
To see the list of widgets that have the Preview feature, add the field 'Has Preview' via the form layout or on the list view of the widgets.
Login widgets do not have the Preview feature available.