pomerium: Websocket error with linkerd dashboard

What happened?

I cannot get the linkerd dashboard live stream of calls to work. I get "websocket error: undefined`.

What did you expect to happen?

I expect to see a stream of calls to my service. I see the live stream if I port-forward. I do not see the live stream if I proxy with pomerium.

What’s your environment like?

• Pomerium version (retrieve with pomerium --version or /ping endpoint): v0.5.1
• Server Operating System/Architecture/Cloud: K8s Rev: v1.14.9-eks-ba3d77

What’s your config.yaml?

apiVersion: v1
data:
  config.yaml: "policy: \n  - allow_websockets: true\n    allowed_groups:\n    - eng@tidepool.org\n
    \   allowed_users: []\n    from: https://glooe-monitoring.production.tidepool.org\n
    \   to: http://glooe-grafana.gloo-system.svc.cluster.local\n  - allow_websockets:
    true\n    allowed_groups:\n    - eng@tidepool.org\n    allowed_users: []\n    from:
    https://linkerd-dashboard.production.tidepool.org\n    to: http://linkerd-dashboard.linkerd.svc.cluster.local:8080\n"
kind: ConfigMap
metadata:
  annotations:
    flux.weave.works/antecedent: pomerium:helmrelease/pomerium
  creationTimestamp: "2019-12-12T18:50:52Z"
  labels:
    app.kubernetes.io/instance: pomerium
    app.kubernetes.io/managed-by: Tiller
    app.kubernetes.io/name: pomerium
    helm.sh/chart: pomerium-4.1.2
  name: pomerium
  namespace: pomerium
  resourceVersion: "26735217"
  selfLink: /api/v1/namespaces/pomerium/configmaps/pomerium
  uid: 525ccabf-1d10-11ea-abeb-02c077500bb6

Additional context

Add any other context about the problem here.