BUG: Unable to purchase tickets using android app

After filling in all the details of the ticket I want, I just get a message saying: "We're sorry but we can't complete your request at the moment due to a technical issue. Please try again later.". This has happened every time I've tried using the app for this over at least 2 months now. I've tried clearing the cache, reinstalling etc. No difference.

Phone: Samsung S8

Android Version: 7.0