There's a problem, that Kibana instance monitoring data collection stops after ElasticSearch cluster is rebooted.
Logstash and ElasticSearch monitoring data is Ok.
Version of all components is up to date: 5.4.0-1
OS: Centos 7, Kernel: Linux 3.10.0-514.10.2.el7.x86_64
Problem was actual in few previous versions too.
To restore data flow, Kibana process should be restarted.
No log messages in Kibana / ElasticSearch logs about this issue.
Hope you'll fix this soon.