Lab 11: linkerd viz check - tap API service is running errors out

I am running this lab on AWS/ Ubuntu 20.04 and getting errors of:

linkerd viz check
linkerd-viz
-----------
√ linkerd-viz Namespace exists
√ linkerd-viz ClusterRoles exist
√ linkerd-viz ClusterRoleBindings exist
√ tap API server has valid cert
√ tap API server cert is valid for at least 60 days
‼ tap API service is running
    MissingEndpoints: endpoints for service/tap in "linkerd-viz" have no addresses with port name "apiserver"
    see https://linkerd.io/2.12/checks/#l5d-tap-api for hints
√ linkerd-viz pods are injected
‼ viz extension pods are running
    pod "prometheus-947f685c4-5z7lr" status is Pending
    see https://linkerd.io/2.12/checks/#l5d-viz-pods-running for hints
‼ viz extension proxies are healthy
    pod "prometheus-947f685c4-5z7lr" status is Pending
    see https://linkerd.io/2.12/checks/#l5d-viz-proxy-healthy for hints
√ viz extension proxies are up-to-date
√ viz extension proxies and cli versions match
√ prometheus is installed and configured correctly
√ can initialize the client
× viz extension self-check
    Error calling Prometheus from the control plane: Query failed: "max(process_start_time_seconds{}) by (pod, namespace)": server_error: server error: 504
    see https://linkerd.io/2.12/checks/#l5d-viz-metrics-api for hints

Any ideas for how to fix would be appreciated!