Kibana can't connect to elasticsearch using self signed certificates

Hi, I have enabled TLS certificates for connection between Kibana and Elasticsearch as described here: Set up basic security for the Elastic Stack plus secured HTTPS traffic | Elasticsearch Guide [7.16] | Elastic

I use rsyslog to send data straight to Elasticsearch and that works fine, I can also use curl to talk to Elasticsearch so certificates are working fine for the https://localhost:9200 URL.

But when I try to do the same with Kibana then all I get is the dreaded "Unable to retrieve version information from Elasticsearch nodes. self signed certificate in certificate chain" log in /var/log/kibana/kibana.log

I used the Elasticsearch-certutil to create a CA, and a certificate/key pair for https using that CA, that also created a kibana directory in the zip file that included a .pem file that I use for telling kibana to trust the Elasticsearch certificate.

Here is the kibana.yml file:

server.publicBaseUrl: "my-dns-server-name"
elasticsearch.hosts: ["https://localhost:9200"]
elasticsearch.username: "kibana_system"
elasticsearch.ssl.certificate: "/etc/kibana/elasticsearch-ssl/elasticsearch-ca.pem"
xpack.encryptedSavedObjects.encryptionKey: "xxxxxxx"
xpack.security.encryptionKey: "xxxxxxx"

And here is the Elasticsearch.yml file:

path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch
network.host: localhost
xpack.security.enabled: true
xpack.security.transport.ssl.enabled: true
xpack.security.transport.ssl.verification_mode: certificate 
xpack.security.transport.ssl.client_authentication: required
xpack.security.transport.ssl.key: elasticsearch-ssl/elasticsearch.key.pem
xpack.security.transport.ssl.certificate: elasticsearch-ssl/elasticsearch.cert.pem
xpack.security.http.ssl.enabled: true
xpack.security.http.ssl.keystore.path: elasticsearch-ssl/http.p12
discovery.type: single-node

All the referenced certificates are from the Elasticsearch-certutil program.

Anyone have ideas on why kibana does not trust the certificate?