Replication problem with Couchbase server 6.6.1

Hi, I have a problem with replication from server A to B. There is configured replication on a bucket between two servers, and if i create a new document it is not replicated. If I remove the bucket on target host and recreate replication for it all the documents are successfully replicated. At some point after creating new documents they again stop randomly being replicated. I checked the goxdrc.log and noticed that the counter “docs_failed_cr_source” is increased.
Could anybody give advice what logs to check, what could be the issue.
Any suggestion would be helpful. Thank you in advance.

docs_failed_cr_source
Number of documents that have failed conflict resolution on the source cluster and not replicated to target cluster.
https://docs.couchbase.com/server/current/rest-api/rest-xdcr-statistics.html

Hi hyunjuV, thank you very much for the reply. I saw that counter in the documentation, but the one thing is unclear why this conflict occurs on target server nobody is doing updates or create a new document. Why it is saying about conflicts of seq number. If I check the seq number on target host it is smaller than the seq number of new documents on the source.