In our QA environment, we use single-node replica-sets to simplify multi-environment deployments (QA, staging & prod all use replica-set configuration regardless of number of nodes)

In our production environment, we would like to migrate from JOURNALLED to REPLICA_ACKNOWLEDGE. However, when using REPLICA_ACKNOWLEDGE with a single-node RS in our QA environments, write operations don't complete. We tried using tags and setting getLastErrorModes but that also failed.

Is there a mechanism for using REPLICA-ACKNOWLEDGE with a single-node replica-set?