Flash of unstyled content

With Sage v9-alpha3, I’m seeing flash of unstyled content on initial page loads on both dev and proxy urls. I am using MAMP. Clean Sage install. No plugins. WP v4.6.1.

Receiving error for missing stylesheet: http://localhost:3000/wp-content/themes/sage/dist/styles/main.css

But, my styles are obviously showing on each change.

My settings (as followed from github repo):

 "publicPath": "/wp-content/themes/sage/",
  "devUrl": "http://mysite.dev:8888",
  "proxyUrl": "http://localhost:3000",
  "cacheBusting": "[name]_[hash:8]"

Sorry, duplicate issue/concern regarding missing stylesheet.