In the blog post we give an example of using http-server --cors='*' -p 8000 . But I've found that http-server --cors="kbn-version" -p 8000 works better. You'll probably want to update server.cors.origin in your config/kibana.yml.
There were other discuss posts which had the same solution: CORS problem in Kibana Map
relevant ticket: https://github.com/elastic/kibana/issues/23904
hopefully this works, good luck
Rashmi