Flutter Fix & iOS Deployment

My Flutter web-app and mobile project has one stubborn obstacle left: every time the code tries to trigger a platform-specific activity the call silently fails—no crash, no log, just nothing. I need a seasoned Flutter developer who can trace that dead end, discover why the channel or method call is being swallowed, and deliver a rock-solid fix that works across Android and iOS.

Once the functionality error is resolved, I also want to wrap up the iOS release workflow. The codebase already builds, but the provisioning, certificate setup and TestFlight/App Store Connect steps aren’t wired into our process yet. I’d like guidance and hands-on help so that I can archive the build in Xcode, push it to TestFlight, and be confident the same pipeline will work for future versions.

Deliverables
• Diagnose and repair the activity-calling issue so the feature executes reliably without side effects.
• Provide a concise summary of the root cause and code changes (Flutter / Dart, native bridge, or config).
• Set up or document the full iOS deployment path: signing, profiles, Xcode project settings, TestFlight upload, App Store submission checklist.
• Quick walkthrough call or annotated notes so I can reproduce the steps myself next release.