That sounds vaguely familiar, and might be the explanation. I guess what still would be in want of explanation is why the website is telling me there are no flights available on any date I search for.

Until very recently you couldn't get the ex-europe latitude pricing in the app, but that changed within the last month or two. Still, even before that I was able to change a flight in the app and get the correct pricing, as long as I originally bought it on the website. So the app somehow had the ability to preserve the better pricing, just not secure it in the first place.