Hey guys, don't change your code, I'm also getting this issue and wasted a few hours on it, but have a look on Apple system status page:
Apple system status page - https://developer.apple.com/system-status/
App Store Connect App Processing - Outage
Yesterday, 12:15 PM - ongoing
Some users are affected
Users are experiencing a problem with this service.
TestFlight - Outage
Today, 12:34 PM - ongoing
Some users are affected
Users are experiencing a problem with this service. We are investigating and will update the status as more information becomes available.