Currently, after each round of getMore commands, the ReshardingChangeStreamsMonitor would only update the resume token in the donor/recipient state document when the number of matched events is non-zero. It is possible for the collection being monitored to not have any matched events (i.e. inserts and deletes) in some round or all rounds. Not updating the resume token means that the monitor would need to resume from the very start if a failover occurs.