Nuxt - disable dev tools in production

I thought dev-tools was automatically disabled in production?

Did a
npm run build [Building for production message]
npm run start

Nuxt @ v2.14.12
▸ Environment: production
▸ Rendering: server-side
▸ Target: server

and dev tools still shows up.

In nuxt.config.js been tinkering with this:

export default {

  debug: process.env.DEBUG_MODE,
  dev: process.env.DEVELOPMENT_MODE,
  ...
}

Even tried hardcoding each as true / false skipping the env file settings and dev tools always there.

Any ideas?

Thanks