Flutter signature invalid when tried on an iOS device

I am trying to run a new Flutter app (the sample app created by flutter create) on an iOS device (an iPhone XS). Xcode manages to install it, but then it crashes with this message:

dyld: Library not loaded: @rpath/Flutter.framework/Flutter
  Referenced from: /private/var/containers/Bundle/Application/BA807438-FA5B-4021-B37D-FC437B2C80CA/Runner.app/Runner
  Reason: no suitable image found.  Did find:
    /private/var/containers/Bundle/Application/BA807438-FA5B-4021-B37D-FC437B2C80CA/Runner.app/Frameworks/Flutter.framework/Flutter: code signature invalid for '/private/var/containers/Bundle/Application/BA807438-FA5B-4021-B37D-FC437B2C80CA/Runner.app/Frameworks/Flutter.framework/Flutter'

If I try flutter run, the app also opens and crashes. And the command keeps waiting forever:

$ flutter run
Launching lib/main.dart on Ferran Maylinch’s iPhone in debug mode...

Automatically signing iOS for device deployment using specified development team in Xcode project: 25D86TPBWG
Running Xcode build...                                                  

 ├─Assembling Flutter resources...                           4.3s
 └─Compiling, linking and signing...                        13.3s
Xcode build done.                                           21.0s
Installing and launching...                                             
(This is taking an unexpectedly long time.)       ⢿

In Xcode I configured a Team (Personal Team) and the Signing Certificate (Apple Development certificate) seems fine because I can install a Hello world Swift project on my device.

Note: I'm not paying an account of Apple Developer Program. Is that absolutely necessary to run Flutter apps on iOS devices?

I have followed the macOS instructions and flutter doctor says I have everything I need for iOS:

[✓] Flutter (Channel stable, v1.12.13+hotfix.5, on Mac OS X 10.15.2 19C57, locale en-ES)

[!] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    ! Some Android licenses not accepted.  To resolve this, run: flutter doctor --android-licenses
[✓] Xcode - develop for iOS and macOS (Xcode 11.3)
[!] Android Studio (version 3.5)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] IntelliJ IDEA Ultimate Edition (version 2019.3.1)
[!] VS Code (version 1.41.1)
    ✗ Flutter extension not installed; install from
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter
[✓] Connected device (1 available)

! Doctor found issues in 3 categories.

As you can see, I used the stable channel, to discard problems with the beta channel, but I usually work in the beta channel to build flutter for web (which works fine).

In the iOS simulator the app works fine too.

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