watchOptions for polling

I struggle configuring/customizing webpack of my sage 9 based theme project:

What I tried:

Add watchOptions with poll: true in resources/assets/config.json:

  "watch": [
  "watchOptions": {
    "aggregateTimeout": 300,
    "poll": true

Add watchOptions to config object in resources/assets/build/

      watchOptions: config.watchOptions,

Started everything for developing/watching:

$ yarn run start
yarn run v0.27.5
$ webpack --hide-modules --watch --config resources/assets/build/webpack.config.js

Webpack is watching the files…

[BS] [HTML Injector] Running...
[BS] Proxying: http://dev:8084
[BS] Access URLs:
       Local: http://localhost:3000
    External: http://dev:3000
          UI: http://localhost:3001
 UI External: http://dev:3001
[BS] Watching files...

Modifying files in folder shared over network (CIFS) isn’t noticed.
Watch with poll worked correctly with sage 8 and gulp - so polling on folder shared over network should work technically.

What am I missing in the config?

Thanks in advance!

After installing everything in Bash on Windows I am able to rule out missing polling as the reason, apparently webpack isn’t triggered by file changes.