Browserify source maps are flattened

Question

I am using grunt-browserify for running browserify:

    options: {
      watch :true,
      transform: ['babelify','envify'],
      external :vendorFiles,
      browserifyOptions: {
        debug: true
      }
    }

When I run this task, the sourcemaps are generated, but the source mappings lack the folder structure information: Chrome displays all of the files as if they are from the root folder. Because of this, any files of the same name in the different directories are masked (except for one lucky file). I tried giving the fullPaths option to browserify; but it doesn't help either.

For babelify, I am using the following .rc file:

{
  "presets": [ "react", "es2015"],
  "plugins": ["babel-plugin-add-module-exports"]
}

I am using Babel 6.0. What could be the reason?