"react-native run-ios --configuration Release" - does not run in Release mode, but Debug instead

[GeoffreyPlitt]

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes.

Environment

$ react-native info
Scanning 819 folders for symlinks in /Users/giro/stardust-app/node_modules (11ms)

Environment:
  OS:  macOS Sierra 10.12.6
  Node:  6.5.0
  Yarn:  0.24.6
  npm:  3.10.3
  Watchman:  4.7.0
  Xcode:  Xcode 9.0 Build version 9A235
  Android Studio:  Not Found

Packages: (wanted => installed)
  react: 16.0.0-alpha.12 => 16.0.0-alpha.12
  react-native: 0.48.0 => 0.48.0

Steps to Reproduce

Run the command in the title of this issue.

Expected Behavior

App runs in Release mode.

Actual Behavior

App runs in Debug mode-- shake menu, etc.

Reproducible Demo

Any skeleton RN app.

[ItsNoHax]

react-native run-ios --variant=release

[GeoffreyPlitt]

Thanks!