Same issue, same signature, another affected team. Team ID: 5M99CP7ZXJ · Bundle IDs: com.speechscan.app and com.speechscan.app.siwatest · Individual membership activated 2026-08-28 by upgrading the existing Personal Team under the same Team ID. Device: iPhone 17 Pro, iOS 27.0, Xcode 26.6, development build. Native sheet renders, Face ID completes, then "Sign Up Not Completed" — ASAuthorizationError 1001, no credential returned, and zero requests reach our identity provider. Device logs show "M2 missing (bad password)" → SRP authentication failure → AKAuthenticationServerError -24000. The public authorize endpoint returns "Invalid client" for both App IDs. Ruled out client-side: com.apple.developer.applesignin = ["Default"] verified in the signed binary and embedded provisioning profile; Sign in with Apple enabled as a primary App ID; capability off/on toggle and regenerated profiles changed nothing. A brand-new explicit App ID and a minimal request with no scopes or nonce fail identically. The same Apple Account completed a first-time Sign in with Apple authorization in another team's app on the same device minutes later. Note on logs: we could not install the Accounts/AuthKit profile — developer.apple.com answers "Your account can't access this page" for the profiles-and-logs page on this paid account, which also disables the on-device sysdiagnose shortcut, and xcrun devicectl device sysdiagnose fails with CoreDeviceCLISupport.DiagnoseError error 0. FB24551524 therefore carries a filtered log collect excerpt instead. Happy to capture it another way if that blocks triage. Feedback Assistant: FB24551524