Auth0 Provider not generating PKCE code challenge

[Javetz]

Hi, I am attempting to set up Auth Code Flow with PKCE.
I followed the docs and managed to get the implicit flow working using the Auth0 provider.

However, the PKCE flow is not working.
The plugin never generates a codeChallenge, the URL looks like it is always attempting the implicit flow.

My nuxt.config.js file is as follows:
Note, I had to use underscores to get the implicit flow to work, but kept both to see if that would make a difference.

modules: [
    // axios is required by @nuxtjs/auth
    '@nuxtjs/axios',
    // https://auth.nuxtjs.org
    '@nuxtjs/auth'
  ],
  auth: {
    redirect: {
      login: '/', // redirect user when not connected
      callback: '/auth/signed-in'
    },
    strategies: {
      local: false,
      auth0: {
        domain: process.env.AUTH0_DOMAIN,
        client_id: process.env.AUTH0_CLIENT_ID,
        scope: ['openid'],
        response_type: 'code',
        grant_type: 'authorization_code',
        grantType: 'authorization_code',
        code_challenge_method: '',
        codeChallengeMethod: '',
      },
      token: {
        property: 'access_token',
        type: 'Bearer',
        maxAge: 1800
      },
      refreshToken: {
        property: 'refresh_token',
        maxAge: 60 * 60 * 24 * 30
      },
    }
  }

[Javetz]

Re-installed the plugin and applied the oauth configs as per documentation and it all worked.

auth: {
    redirect: {
      login: '/login', // redirect user when not connected
      callback: '/auth/callback'
    },
    strategies: {
      local: false,
      oauth2: {
        scheme: 'oauth2',
        domain: process.env.AUTH_DOMAIN,
        clientId: process.env.AUTH_CLIENT_ID,
        scope: ['openid','profile'],
        responseType: 'code',
        grantType: 'authorization_code',
        codeChallengeMethod: 'S256',
        endpoints: {
          authorization: process.env.AUTH_ENDPOINT,
          token: process.env.AUTH_TOKEN_ENDPOINT,
          userInfo: process.env.AUTH_USER_INFO_ENDPOINT,
          logout: process.env.AUTH_LOGOUT_ENDPOINT
        },
        token: {
          property: 'access_token',
          type: 'Bearer',
          maxAge: 1800
        },
        refreshToken: {
          property: 'refresh_token',
          maxAge: 60 * 60 * 24
        },
      }
    }
  }