how to preview the App Store page before app is released?

We are developing a new app and it's loaded on the App Store for testing (TestFlight). My testers can get the app and are testing away. I am building all of the assets for the App Store page, but I can't find how to see a preview of the page. There is a link on the App Store Connect web page under "General -> App Information" labeled "View on App Store." That link takes me to the App Store on my Mac but I get an error "This app is currently not available in your country or region." I have ALL countries selected under "Pricing and Availability" so I don't know why it won't show me the preview of the App Store page.

Any help?

thanks,