TestFlight: "requested app is not available", Beta App Review error, tester stuck on "Invited" – same on two app records

Hello,

I am an individual developer with a paid Apple Developer Program membership. TestFlight does not work for my account, and I have run out of ideas. Apple Developer Support case 103011239704 has been open since Oct 28 without a reply.

Symptoms

  1. Submitting a build for external testing (Beta App Review) fails with: "There was an error processing your request".
  2. An internal tester (myself) stays in status "Invited" forever and no invitation email arrives. Re-sending does not help.
  3. Installing the build from the TestFlight app on iPad fails with: "The requested app is not available or does not exist".
  4. The first build I uploaded shows "Expired" even though it was recent.
  5. Saving Test Information succeeds, but submitting the build for external testing fails with a validation / processing error on both app records.

What I have checked

  • Free Apps agreement is active. DSA trader status is active. (Paid Apps shows pending tax info; the app is free.)
  • iPad runs iPadOS 26.4.1; the app's minimum deployment target is iOS 17.6.
  • Tried a different browser. macOS 26.2 on the Mac.
  • Created a second app record with a new bundle ID and uploaded a new build there. Same errors.

So the problem seems to be tied to the account, not to a single app record.

I know this seems to be quite common error. Is there something in the account setup (agreements, tax, trader info, tester setup) that could cause TestFlight to behave like this? If it is a server-side issue, how can I get it escalated?

Also, if Developer Support and Feedback Assistant do not respond for weeks, where else can I get help? Is there an escalation path, for example a Developer Technical Support request, a phone/callback option, or a specific contact for App Store Connect account problems? Any advice from people who got a stuck TestFlight account fixed would be very welcome.

Feedback Assistant report: FB25399719

Thank you for any help.