Sage 9 - js on save doesn't update

I think it’s something to do with the urls used in the config.json.

I managed to fix this issue by changing my URLS to below however now whenever I make a change to a JS file browsersync constantly refreshes. And I get this error -

Seems to happen only on dev URLs with a subfolder (i.e. multisite sub-sites). I’ve tried playing the forward slashes on the publich path and the dev URL but no luck.

{
  "entry": {
    "main": ["./scripts/main.js", "./styles/main.scss"],
    "customizer": ["./scripts/customizer.js"]
  },
  "publicPath": "/wp-content/themes/sagetheme",
  "devUrl": "multisite.test/test",
  "proxyUrl": "http://localhost:3000",
  "cacheBusting": "[name]_[hash:8]",
  "watch": ["app/**/*.php", "config/**/*.php", "resources/views/**/*.php"]
}