Ivy --> Maven migration: Roadblock

I’m trying to convert an Ivy Vaadin 8 project to Maven. Mostly, it seems perfect - no errors or warnings, Theme and (for now) AppWidgetset build without errors, .war file deployed to Tomcat 9 host seems to load and run normally. The Tomcat logs indicate the startup process is normal, and the app is generating progress entries in the log as expected.

But there is no content in the browser. The widgetset doesn’t lead to the expected loading of a UI. The attachment shows a much smaller response than expected from the widgetset. Loading stalls, spinner spins.

Maven clean, Eclipse clean and rebuild, maven package, WAR file looks good…

Where am I going wrong?

Eclipse 2019-03, Maven simple archetype, Vaadin 8.8.2