I have created a web app using the ArcGIS Online Web App Builder. I want to use the attribute table widget to access the data in the layers. When I configure the attribute table widget, one of the layers (call it layer "A") does not show in the list, so I can't display it in the table. However, if I open the "Layer List" widget, layer A is displayed. I can click the dropdown button next to layer A, select "Open attribute table", and then the data displays perfectly in the attribute table widget. Unfortunately, I can't save the web app in the configuration that displays layer A. I can't see any difference between the properties for layer A and the other layers that I am able configure. Any ideas?