The pop up displays correctly in map viewer. You should see a list of all the past traffic count records, with a header telling you the start date of the count.

But in the instant app, it only displays the date for the most recent record. This was functioning correctly a couple of months ago. If you click on the related record, it shows a more detailed pane with the correct date, so I know something isn't wrong with the underlying data, backed up by the fact that it works correctly in Map Viewer.

Here is the app. We use it as a public facing way to share the traffic data we collect every year.
NRPC Traffic Count Viewer