Flutter inconsistent button colors

flutter_buttons.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: lightTheme,
      //theme: lightScheme,
      home: Scaffold(
        appBar: AppBar(
          title: Text('Action Buttons'),
          actions: [
            OutlinedButton( // not visible on light theme
              child: Icon(Icons.done_outline), 
              onPressed: () => {},
            ),
            TextButton( // not visible on light theme
              child: Icon(Icons.article), 
              onPressed: () => {},
            ),
            ElevatedButton( // visible on light theme
              child: Icon(Icons.done), 
              onPressed: () => {},
            ),
          ]
        ),
      ),
    );
  }
}

final lightTheme = ThemeData.light(); // issue

final lightScheme = ThemeData(
  colorScheme: ColorScheme.light(),
);