What could cause repqueue records to get stuck with publish_status= "New"?

Oracle Xcenter 21.0.3 (On Prem version)

We've had two production incidents in the past 3 weeks where one of the replication threads in one of our Xcenter servers suddenly stopped publishing to dtv schema.

Specifically, if we run this query, you can expect huge count (ex. 100K records) to be in NEW status.

select * from repqueue.rpl_replication_data
where publish_status ='NEW'

Terminating the server to force server re-clustering resolved the issue. All records got replicated eventually but we don't know how it got stuck in the first place. We've looked into xcenter

What are the things that we could look for when investigating this issue? What can we enable in the logging so we could catch the issue going forward?