Today I created a single node elasticsearch + kibana 6.2.2 deployment on azure. When everything was done provisioning, I noticed the CPU was pegged on the kibana VM. I connected over ssh and found that I had to remove the xpack lines from kibana.yml because it just repeated this forever:
589,"message":""xpack.security.encryptionKey" and "xpack.reporting.encry
ptionKey" settings were not applied. Check for spelling errors and ensure
that expected plugins are installed and enabled."}
After commenting out those lines I was able to start kibana and load the UI. I haven't dug into xpack plugin issue any more (it's bed time) but my expectation is that it would have worked without intervention.