Same signature here, on an App ID created in August 2026. Team ID: 276UBMJFVS Bundle ID / Client ID: com.openshimmy.open (App ID V2XX9T4FG9, platform Universal) App ID created: 2026-08-12; Sign in with Apple capability enabled 2026-08-15 (APPLE_ID_AUTH, PRIMARY_APP_CONSENT) Feedback Assistant: FB24734174 App: OPEN, App Store id 6800488516 (live since 2026-08-13, currently 1.0.17) Symptom: the native sheet renders, the user authenticates, then "Sign Up Not Completed". ASAuthorizationController returns ASAuthorizationError 1000 (our client instrumentation records the code; 1001 would be recorded as well). No credential, and zero requests ever reach our backend. Zero Apple identities have ever been created for this app; Google sign-in on the same devices works. Verified: com.apple.developer.applesignin = ["Default"] in the signed App Store binary and its embedded provisioning profile; bundleIdCapabilities shows PRIMARY_APP_CONSENT; membership, certificate and profile all valid. Reproduced on: multiple iPhones and Apple IDs since 2026-08-18, across every App Store build from 1.0.6 to 1.0.17 (from timing, App Review devices included). One anomaly for the record: a single iPhone did receive a credential from the sheet on 2026-08-17, and the same phone hit "Sign Up Not Completed" the next day. Sysdiagnose with the Accounts/AuthKit profile available on request as soon as we have an affected device in hand.