I have 2 macOS Applications on App Store Connect. (not iOS) Both working with many users for some time. One Testflight User is getting the Email on one Application without the "View in Testflight" Button. Which, I think, is needed to connect the Testflight to the App. I can not find the difference and all other users can install it. I tried removing him from the Testing List and adding him many times. Sending 20 new Versions ... nothing works. Like I said. The second application was working. And the Difference is only the Email. One is coming with the Button "View in Testflight" and the other are not.