iOS app crashes in Release Config (but works in Debug)

[sophiabk]

• Review the documentation: https://facebook.github.io/react-native
• Search for existing issues: https://github.com/facebook/react-native/issues
• Use the latest React Native release: https://github.com/facebook/react-native/releases

Environment

React Native Environment Info:
System:
OS: macOS High Sierra 10.13.6
CPU: x64 Intel(R) Core(TM) i7-7660U CPU @ 2.50GHz
Memory: 1.89 GB / 16.00 GB
Shell: 5.3 - /bin/zsh
Binaries:
Node: 10.9.0 - ~/.nvm/versions/node/v10.9.0/bin/node
npm: 6.2.0 - ~/.nvm/versions/node/v10.9.0/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 11.4, macOS 10.13, tvOS 11.4, watchOS 4.3
Android SDK:
Build Tools: 23.0.1, 27.0.3, 28.0.1
API Levels: 23, 24, 25, 26, 27, 28
IDEs:
Android Studio: 3.1 AI-173.4819257
Xcode: 9.4.1/9F2000 - /usr/bin/xcodebuild
npmPackages:
react: ^16.4.2 => 16.4.2
react-native: ^0.56.0 => 0.56.0
npmGlobalPackages:
react-native-cli: 2.0.1

Description

1. App builds perfectly in debug mode (on device and simulator)
2. Android app builds in both debug and release perfectly.
3. THE PROBLEM: iOS app loads in release mode and immediately crashes on launch screen (e.g. build succeeds and then crashes)
4. Crash Report is here: http://crashes.to/s/11df9058d1f
   Fatal Exception: NSInvalidArgumentException
   -[RCTRootView reactTag] unrecognized selector sent to instance 0x139e023c0

What I've tried already (but didn't help)

• Building Active Architecture Only
• Not stripping dead code / Stripping dead code
• Checking Headers
• Checking Linked Binaries
• Checking Link Flags
• Reinstalling NPM/Pods
• [0.56][RELEASE] Bundler cuts off some used babel helpers in release build (decorators issue) #20150

What I think might be wrong

• Something with Babel 7 and React-Native
• Something with React-Native-Navigation

[poprapas]

how to a solution?