Error - Document Not Found In couchbase

I have observed one strange issue with the couchbase. Where in few buckets, documents were not found (All the data was deleted and the row was marked with grey and messgae Error : document not found)

Our couchbase is installed on centOS and i didn’t get anything specific in the logs related to the error.

Also, I checked on the path – /opt/couchbase/var/lib/couchbase/data and can see data files present over there.

Note - This was the warning message i got - Warning: couchbase-server.service changed on disk. Run ‘systemctl daemon-reload’ to reload units.