The ticket purchase screen may repeatedly appear if the account you logged in from on the web and the application are different. In this case, please log out of your account on the app and re-login with the account you bought the ticket on.
(You can log out from “Settings and Privacy”)
You can double check if you are logged in with separate accounts. On the web browser, see the icon on the upper right corner; for the app, see the icon on the upper left. Tapping on the icon will display the user ID as “@xxxxx”, so ensure that these IDs are the same for both accounts.