Using --no-tree-shake-icons means no icons appear after building

Question

Currently, I am getting the error This application cannot tree shake icons fonts. When I use --no-tree-shake-icons, none of the material icons appear on the application. I am not sure how to fix this as I cant add const to my icons as they aren't constant:

iconData: IconData(document.data()['ref'], fontFamily: 'MaterialIcons')

Edit: This is my pubspec.yaml folder:

version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  table_calendar: ^2.3.3
  wave_progress_widget: ^0.0.1
  liquid_swipe: ^1.4.3
  firebase_helpers: ^0.2.2
  firebase_messaging: ^7.0.3
  carousel_slider: ^3.0.0
  google_fonts: ^1.1.2
  date_field: ^1.0.4
  cloud_firestore: ^0.14.0+2
  intl: ^0.16.1
  googleapis: ^0.55.0
  googleapis_auth: ^0.2.12
  url_launcher: ^5.5.0
  get_it: ^5.0.6
  flutter:
    sdk: flutter
  firebase_core: ^0.5.3
  firebase_database: "^4.4.0"
  cupertino_icons: ^1.0.0

dev_dependencies:
  flutter_test:
    sdk: flutter
  
  flutter_launcher_icons: "^0.8.1"

flutter_icons:
  image_path: "icon/icon.png" 
  android: true
  ios: true

assets:
  - assets/

flutter:

  uses-material-design: true

I would appreciate any help!