My SHC captain is reporting this:
Search peer <current_captain> has the following message: The search head cluster captain (https://<previous_captain>:8089) is disconnected; skipping configuration replication
I've since run a rolling restart, but the message persists.
In general, you will find more errors or warnings around that message. Sometimes it is related to bundle from deployer.
Other time, it is related to configuration replication errors due to corrupted file or large contents or something. If you find which file or configuration is related to this error, you can try to delete or remove it and see if it helps.
For detail of troubleshooting, you might want to file a Support case with a splunk diag file so that Support engineer can take look into more detail.
Is the previous captain actually running?
Check that the cluster is in a working state? Check with the status command.
Yes. Cluster is 100% up. Previous captain reporting normally.