Scheduled Apex Doesn't Read New Custom Metadata

As mentioned by @cropredy and their linked answer, this was due to serialization of the schedulable class. Although it's obvious now, it is worth noting that the serialization extends to all code that may be run in the constructor. My class looked something like this:

public class MySchedulable implements Schedulable {

  @TestVisible
  private Orchestrator orchestrator = new Orchestrator();

  public void execute(SchedulableContext context) {
    orchestrator.start();
  }

}

The field map class that referenced the custom metadata is instantiated by a service class that itself is instantiated by the orchestrator and is then executed in the queueable. A simple rewrite will prevent any serialization when running in production, but still allow dependency injection for tests.

public class MySchedulable implements Schedulable {

  @TestVisible
  private Orchestrator orchestrator;

  public void execute(SchedulableContext context) {
    (orchestrator ?? new Orchestrator()).start();
  }

}