Working Angular 6 SCSS Sourcemaps

enable-sourcemaps.patch

--- node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/styles.js
+++ node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/styles.js
@@ -220,7 +220,7 @@ function getStylesConfig(wco) {
                 options: {
                     ident: 'embedded',
                     plugins: postcssPluginCreator,
-                    sourceMap: cssSourceMap
+                    sourceMap: cssSourceMap ? 'inline' : false
                 }
             },
             ...use

patch.js

const fs = require('fs');
const sh = require('shelljs');

const PATCH_LOCK = 'node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/.patched-enable-sourcemaps';

// You can generate patch file by `git diff` or use `diff -Nur`
if (!fs.existsSync(PATCH_LOCK)) {
    sh.exec('patch -p0 -i tools/cli-patches/enable-sourcemaps.patch');
    sh.touch(PATCH_LOCK);
}

Usage instructions here

WARNING:

The patch might break with any future version of @angular-devkit. If this happens you’ll need to generate another patch file using git diff.