PostCSS: PurgeCSS not working when task is run

Question

I'm currently trying to remove unused CSS from a project's stylesheets. I have a gulp task sass where all the compiling is being done. I'm using postcss and a plugin for purgecss. However, when I run the sass task purgecss doesn't seem to be working.

gulp.task('sass', () => gulp.src(`${SRC}/scss/style-*.scss`)
  .pipe(sourcemaps.init())
  .pipe(gulpSass({
    includePaths: ['node_modules', `${PATTERNS_ACCESS}/src/`]
    .concat(require('bourbon').includePaths)
  })
  .on('error', gulpSass.logError))
  .pipe(postcss([
    purgecss({
      content: ['./views/**/*.twig']
    }),
    autoprefixer(),
    mqpacker({sort: true}),
    cssnano()
  ]))
  .pipe(hashFilename({format: HASH_FORMAT}))
  .pipe(sourcemaps.write('./'))
  .pipe(gulp.dest('./assets/styles'))
);

Above if you notice purgecss I pass it the path to to the templates it should remove the css from. Using the PostCSS API following the documentation, I add the directory of the templates:

const purgecss = require('@fullhuman/postcss-purgecss')
postcss([
  purgecss({
    content: ['./src/**/*.html']
  })
])

Is there anything I should add to the configuration on the purgecss besides content? what can the issue be?