Flutter Web and Firebase Hosting Blank Screen

I'm trying to create a website using Flutter Web and Firebase.

I used this tutorial: https://medium.com/@abhijeetdash1999/flutter-web-with-firebase-hosting-82c341989b37

I followed all the steps and keep getting a blank screen. I found many people having the same issue but fixed it by rewriting the index.html in the build folder with the one in the project folder so it references the Flutter main.dart.js

Any ideas? I've been trying for 2 days and I'm sure I just need a fresh pair of eyes for this.