Webpack conditional SCSS alias

Question

I have an Angular project with custom webpack config. In webpack.config.js file there's an conditional alias setup, which is aliasing to a .scss file based on an variable received from other js file. The value of this variable depends on a build (it's basically an environment variable, but stored elsewhere).

If I output the resulting config object, the alias value is pointing to the correct file. The first build does everything correctly, but the second one (using different environment) starts to act strange - it loads scss from previous build, instead of new one.