Major Description
A part of the replica set info provider (namely, the LocalChanges), uses the instance cluster id to find out whether Oak is being run in cluster.
However, the way in which MongoDocumentStore provides this clusterId to the LocalChanges class is not correct. It's taken from the DocumentMK.Builder, which works only for the case when it's being set explicitly in the configuration and doesn't work if Oak gets its clusterId automatically.
As a result, if the clusterId isn't set in the configuration, the LocalChanges class remains disabled and doesn't allow to use the secondary Mongo instances for find() and query() requests.