On failover, the new config primary recovers migrations and uses the BalancerConfiguration class' default maxChunkSize of 64 here without trying to load any maxChunkSize user setting from config.settings. Thus, a chunk larger than what the user has defined as jumbo may get moved.

If the new primary was primary previously, it may have the correct maxChunkSize value set in the BalancerConfiguration instance: though it would be stale, whether right or wrong.

BalancerConfiguration::refreshAndCheck should be called before balancer recovery, as it is done before running every auto balancing round.