Why is webpack --watch not updating when specific files are updated

using the old watcher plugin seems to resolve the issue for my needs. Done in my configuration via:

plugins: [
    new webpack.OldWatchingPlugin()
],

I also just came across this issue and it was because the case of the string for the file in the 'require' function call was different than the filesystem. It was still being included in the bundle, but it wasn't being picked up for live re-bundling with webpack-dev-server. Fixing the require call to have the right case fixed it.