Invalid sync source in mongodb config server
As I am able to see in your error log file such as error Fetcher stopped querying remote oplog with error: InvalidSyncSource: sync source

As per MongoDB jira documentation here It seems that the common cause for the remote replSetUpdatePosition failing with those error codes NodeNotFound,NotMasterOrSecondary and InvalidReplicaSetConfig would be a change in config. Config changes currently will cause the oplog fetcher to fail because it will detect a change in the config version contained in the oplog query metadata. Subsequently, after exiting the oplog fetcher, we will go back to the sync source resolver which has its own blacklisting logic.

For your further ref here