Elasticsearch randomly returns empty results for a query which have entries in index

Question

We are using Elastic 6.0 and Nest with 1 primary and 3 replicas. Sometimes when we run a query it would return empty results and when we immediately run it again it would return the appropriate results. This happens randomly and I couldn't see any pattern. I do not know what could be causing this and I can provide more info.

Thanks

Glow

you are getting the hits as null ,or not getting any response from ES after firing query? – Mesne

have you found any solution for this issue? – Junina