The “Featured/Popular” widget is time-sensitive. Depending on your settings on the widget in “Appearance > Widgets” your downloads may not appear in the widget.
If your date range is “One Week” then only downloads published within the current calendar week will be queried to be determined if they are featured or popular. If a download was published and featured two weeks ago it will not appear. If a download has no sales in the current week, it will not appear.
If no results are found at all, the entire widget will be hidden.