Hi rams,
The official download docs instruct to set ent_search.auth.source to standard, but it looks like the Kibana integration requires that elasticsearch-native or SAML is used.
This previous thread may be of use: Connect Kibana Workplace Search - #4 by Sean_Story
Can you please try that and let me know if it resolves your issue? If not, can you please post your configuration yml files for Elasticsearch, Kibana, and Enterprise Search?
Thank you!