ScheduleNewOrchestrationInstanceAsync fails when scale controller scaling in

I've recently started using Netherite (Microsoft.Azure.Functions.Worker.Extensions.DurableTask.Netherite" Version="1.5.1") and have been seeing a few errors when starting orchestrations.

Orchestrations start fine most of the time, but occasionally I see the following error:

When starting an orchestration, as follows:

            var ingestionOrchestrationSpec = new IngestionOrchestrationSpec(etc...);
            var orchestrationInstanceId = $"ingestions.{tenant.ProjectId}.{pointcloud.Id}";
            await client.ScheduleNewOrchestrationInstanceAsync(nameof(IngestionsCreateAsyncOrchestrator), ingestionOrchestrationSpec, new StartOrchestrationOptions { InstanceId = orchestrationInstanceId });

This exception is thrown:

Exception: Grpc.Core.RpcException: Status(StatusCode="Unknown", Detail="Exception was thrown by handler.")
   at Microsoft.DurableTask.Client.Grpc.GrpcDurableTaskClient.ScheduleNewOrchestrationInstanceAsync(TaskName orchestratorName, Object input, StartOrchestrationOptions options, CancellationToken cancellation)
   at TrimbleGeospatial.Seurat.ApiApp.Functions.Ingestions_Create.Run(HttpRequestData req, DurableTaskClient client, FunctionContext functionContext, String projectId, String pointcloudId)

Start with ScheduleNewOrchestrationInstanceAsync and the reported Grpc.Core.RpcException while the scale controller is scaling in. Reproduce the failure using the orchestration call shown, then trace the handler and add coverage demonstrating that scheduling succeeds during scale-in without the exception.