Redirected to login page after Dex successful login

[zxtariel0512]

Hi there! I have been struggling with this issue for days and would love to have any suggestion or help.

Background
I deployed Kubeapps using helm chart on a TKC, and am able to access it in browser and login to see all my apps and deploy new app using ServiceAccount token. I am now trying to configure it to use Dex for login. I deployed Dex on the same TKC, edited the helm chart value of Kubeapps to enable auth-proxy for Dex.

Problem
After accessing Kubeapps using http://localhost:8080, I clicked the button for Dex login, and got successfully redirected to Dex login page. I entered the default username and password ([email protected]/12341234), and got successfully authenticated. But then I got redirected back to Kubeapps login page. It seems that Kubeapps does not think I am authenticated.

Currently using...
Below is the useful fields I am using in Kubeapps helm chart:

authProxy:
  external: false
  oauthLoginURI: /oauth2/start
  oauthLogoutURI: /oauth2/sign_out
  skipKubeappsLoginPage: true
  provider: oidc
  clientID: xxx
  clientSecret: xxx
  cookieSecret: xxx
  cookieRefresh: 2m
  scope: "profile email groups openid"
  extraFlags:
  - --cookie-secure=false
  - --ssl-insecure-skip-verify=true
  - --oidc-issuer-url=http://dex.auth.svc.cluster.local:5556/dex
  - --redirect-url=http://localhost:8080/oauth2/callback
  - --user-id-claim=email

And below is my Dex configmap:

apiVersion: v1
kind: ConfigMap
metadata:
  name: dex
data:
  config.yaml: |
    issuer: http://dex.auth.svc.cluster.local:5556/dex
    storage:
      type: kubernetes
      config:
        inCluster: true
    web:
      http: 0.0.0.0:5556
    logger:
      level: "debug"
      format: text
    oauth2:
      skipApprovalScreen: true
    enablePasswordDB: true
    staticPasswords:
    - email: [email protected]
      hash: $2y$12$4K/VkmDd1q1Orb3xAt82zu8gk7Ad6ReFR4LCP9UeYE90NLiN9Df72
      # https://github.com/dexidp/dex/pull/1601/commits
      # FIXME: Use hashFromEnv instead
      username: user
      userID: "15841185641784"
    staticClients:
    # https://github.com/dexidp/dex/pull/1664
    - idEnv: OIDC_CLIENT_ID
      redirectURIs:
      - http://localhost/oauth2/callback
      - http://localhost:8080/oauth2/callback
      name: 'Dex Login Application'
      secretEnv: OIDC_CLIENT_SECRET

Workaround
I am not 100% sure but I think my Kubeapps should be okay because I was able to login, view apps, and deploy new app using ServiceAccount token. And I have checked the Dex pod to make sure that from the Dex's view, I am successfully authenticated.
So I feel like the issue is about the redirect URI... I followed the official documentation to set it to be http://localhost:8080/oauth2/callback. I have verified that this callback URI is indeed called after Dex authentication. But somehow it always takes me back to Kubeapps login page.

Thanks! Any opinion would help!