Thank you for the reply!
The permissions seem okay to me. I will enable debug for the logging and see if that gives me a clue.
bash-4.4$ ls -la /usr/share/kibana/config/
total 20
drwxrwxr-x 1 kibana root 4096 Jul 23 00:41 .
drwxrwsr-x 1 kibana root 4096 Jun 10 20:59 ..
drwxrwsrwt 3 root kibana 100 Jul 23 00:40 ca
drwxrwsrwt 4 root kibana 120 Jul 23 00:40 certs
-rw-r--r-- 1 root kibana 546 Jul 23 00:40 kibana.yml
-rw-rw-r-- 1 kibana root 216 Jun 10 20:24 node.options
bash-4.4$ ls -la /usr/share/kibana/config/certs
total 4
drwxrwsrwt 4 root kibana 120 Jul 23 00:40 .
drwxrwxr-x 1 kibana root 4096 Jul 23 00:41 ..
drwxr-sr-x 2 root kibana 60 Jul 23 00:40 ..2021_07_23_00_40_51.279187955
lrwxrwxrwx 1 root root 31 Jul 23 00:40 ..data -> ..2021_07_23_00_40_51.279187955
lrwxrwxrwx 1 root root 31 Jul 23 00:40 elastic-certificates.p12 -> ..data/elastic-certificates.p12
drwxrwsrwt 3 root kibana 100 Jul 23 00:40 kibana
bash-4.4$ ls -la /usr/share/kibana/config/ca
total 4
drwxrwsrwt 3 root kibana 100 Jul 23 00:40 .
drwxrwxr-x 1 kibana root 4096 Jul 23 00:41 ..
drwxr-sr-x 2 root kibana 60 Jul 23 00:40 ..2021_07_23_00_40_51.091807926
lrwxrwxrwx 1 root root 31 Jul 23 00:40 ..data -> ..2021_07_23_00_40_51.091807926
lrwxrwxrwx 1 root root 27 Jul 23 00:40 elasticsearch-ca.pem -> ..data/elasticsearch-ca.pem
bash-4.4$ ls -la /usr/share/kibana/config/certs/kibana
total 0
drwxrwsrwt 3 root kibana 100 Jul 23 00:40 .
drwxrwsrwt 4 root kibana 120 Jul 23 00:40 ..
drwxr-sr-x 2 root kibana 60 Jul 23 00:40 ..2021_07_23_00_40_52.708615512
lrwxrwxrwx 1 root root 31 Jul 23 00:40 ..data -> ..2021_07_23_00_40_52.708615512
lrwxrwxrwx 1 root root 24 Jul 23 00:40 kibana-server.p12 -> ..data/kibana-server.p12
bash-4.4$