same issue, submitted build using xcode 15.0.1, appstoreconnect says can't publish it due to "This build is using a beta version of Xcode and can’t be submitted. Make sure you’re using the latest version of Xcode or the latest seed release found on the releases tab in News and Updates"... I'm not using beta version of xcode

signed out of icloud, logged in with account added to sandbox (had to verify email in the settings too), and still getting "Invalid Card" error while trying to add any test cards. This is all on the blank iphone dedicated only to apple pay. Anyone else (or Apple?) ever got this to work following instructions on https://developer.apple.com/apple-pay/sandbox-testing/?