Do you have to wait for firebase hosting to "process" files before they're available?

Question

I'm creating a react app with create react app and deploying to firebase hosting. I've done this several times, never without a hitch. But, many of the assets in my public directory are giving 404 errors:

When I look at hosting in project console, it seems like the files are present:

I've pieced together online that files might only become available in Firebase Hosting after Firebase "processes" the files, is this the case? Someone suggested in this thread from the firebase forums that it might take some time before the assets become available.

Or maybe I've run up against some kind of limit with the free tier of firebase hosting?

Additional Info:

firebase.json

{
  "hosting": {
    "public": "build",
    "ignore": ["firebase.json", "**/.*", "**/node_modules/**"],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}