Sourcemap is not being output correctly

[fablrdigital]

I am using this plugin to generate sourcemaps for our CSS output but all it is outputting is the following.

{"version":3,"file":null,"sources":[],"sourcesContent":[],"names":[],"mappings":""}

Here is an example of our vite.config.js

import { defineConfig } from "vite";
import cssSourcemap from 'vite-plugin-css-sourcemap';

export default defineConfig({
  plugins: [cssSourcemap({
    enabled: true,
    extensions: ['.scss', '.css'],
  })],
  build: {
    cssMinify: true,
    rollupOptions: {
      input: "assets/scss/main.scss",
      output: {
        assetFileNames: `[name].[ext]`,
      },
    },
  },
});

CSS is generated fine but mapping is not generated. Below is our package.json FYI.

{
  "name": "sample",
  "private": true,
  "version": "0.0.Z",
  "type": "module",
  "scripts": {
    "dev": "vite",
    "build": "vite build",
    "build:watch": "vite build --watch",
    "preview": "vite preview"
  },
  "devDependencies": {
    "sass": "^1.89.2",
    "vite": "^6.3.5",
    "vite-plugin-css-sourcemap": "^1.0.2"
  },
  "dependencies": {
  }
}

Hope someone can help or advise what might be happening here. I tried everything described in #3 and it didn't help.

[MarioCadenas]

could you also provide some repo or files to reproduce it? thank you @fablrdigital !