Do you have both http and https turned on there? I'm not a big developer on docker at the moment but before when there were problems:
I upgraded to 7.6.0 today.
I wanted to try Detections, but I'm getting error (below) when clicking "load prebuilt detection rules".
My complete Kibana config:
---
## Default Kibana configuration from Kibana base image.
## https://github.com/elastic/kibana/blob/master/src/dev/build/tasks/os_packages/docker_generator/templates/kibana_yml.template.js
#
server.name: kibana
server.host: "0"
elasticsearch.hosts: [ "http://elasticsearch:9200" ]
xpack.monitoring.ui.container.elasticsearch.enabled: fa…
The solution usually was they had to ensure they were using the SSL/https within docker to be able to use the API keys feature.