When applying the Filter function in the Summary widget of ArcGIS Web AppBuilder, the Field value selected in the Filter drop-down do not automatically update the summarized features in the widget panel.
Summary widget reads the filter information in real-time in the latest ArcGIS Online 4.2. The results will automatically refreshed when the filter changes.
解决办法
For results to appear:1. Zoom in or out in the application or deselect then reselect the widget. 2. The summarized results in the widget panel are now updated.