Kibana dashboard gives 504: Gateway Timeout

Issue

Attempting to access Kibana gives a timeout error. Logs look something like the following:

[openshift@server.node.example.com]$ oc logs logging-kibana-1-db9pw -c kibana-proxy
2019/06/17 21:02:08 provider.go:530: Performing OAuth discovery against https://10.0.0.1/.well-known/oauth-authorization-server
2019/06/17 21:02:08 provider.go:576: 200 GET https://10.0.0.1/.well-known/oauth-authorization-server {
  "issuer": "https://ocpmaster.example.com:443",
  "authorization_endpoint": "https://ocpmaster.example.com:443/oauth/authorize",
  "token_endpoint": "https://ocpmaster.example.com.com:443/oauth/token",
  "scopes_supported": [
    "user:check-access",
    "user:full",
    "user:info",
    "user:list-projects",
    "user:list-scoped-projects"
  ],
  "response_types_supported": [
    "code",
    "token"
  ],
  "grant_types_supported": [
    "authorization_code",
    "implicit"
  ],
  "code_challenge_methods_supported": [
    "plain",
    "S256"
  ]
}
2019/06/17 21:02:08 oauthproxy.go:201: mapping path "/" => upstream "http://localhost:5601/"
2019/06/17 21:02:08 oauthproxy.go:228: OAuthProxy configured for  Client ID: kibana-proxy
2019/06/17 21:02:08 oauthproxy.go:238: Cookie settings: name:_oauth_proxy secure(https):true httponly:true expiry:168h0m0s domain:<default> refresh:disabled
2019/06/17 21:02:08 http.go:56: HTTP: listening on 127.0.0.1:4180
2019/06/17 21:02:08 http.go:96: HTTPS: listening on [::]:3000
2019/06/17 21:04:29 reverseproxy.go:321: http: proxy error: context canceled
2019/06/17 21:04:52 reverseproxy.go:321: http: proxy error: context canceled
2019/06/17 21:05:02 reverseproxy.go:321: http: proxy error: context canceled