Constant result searching App Store: "Your search had no results

Without fail, anytime I type the name of any app in the Search window of the App Store on my MBP, the result is always, invariably, without fail, the same: "Your search had no results. Try searching again." Doesn't matter what I'm looking for. Last time I checked TripAdvisor had an app...but the App Store can't find it...the only way for me to find an ap is to click on "Categories", then keep drilling down until I find the app I want, which is a labourious and silly way to have to do it. Any ideas what's going on? Screenshot attached. Thanks..