Caching in non-library mode throws exception and question regarding performance tests

[ChrisWint]

I was playing around with the PerformanceTest example and wanted to try the multithreaded non-library mode. If I understood the config correctly this is achieved by setting the OwnedThreads stream scheduler.
However, if I do this a simple GroupAggregate will cause the Cache()call to throw in StreamableIO.cs:179 with a NotImplementedException.
I included the full code to reproduce the issue below including a dump of the config. Is there something I am missing that I need to do in order to use Cache() in multithreaded mode or is this a bug?

I have tried multiple configuration combinations for the OwnedThreads scheduler but all result in the same error, same with using intervals instead of StartEdge events. I encountered the same issues for equi-joins as well, but the grouping example is simpler.

If caching is not inteded for multithreaded modes is there a way to achieve similar, efficient in-memory caching of the results that I could use to measuer the performance of my queries?
And are there other settings in the config I should fine-tune to achieve the best throughput for multi-threaded execution?

Thanks!

public static void Main(string[] args)
        {
            Config.StreamScheduler = StreamScheduler.OwnedThreads(2);

            var rand = new Random();
            var dataset =
              Observable.Range(0, 100000)
                  .Select(e => StreamEvent.CreateStart(1, new { field1 = e % 1000, field2 = rand.Next(1, 100) }))
                  .ToStreamable()
                  .SetProperty().IsConstantDuration(true, StreamEvent.InfinitySyncTime)
                  .Cache();

            var query = dataset.Where(d => d.field1 < 950).GroupAggregate(
                d => d.field1,
                d => d.Sum(d => d.field2),
                d => d.Count(),
                (key, sum, count) => new { key.Key, sum, count });

            // Run the query
            var sw = new Stopwatch();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            sw.Start();

            var result = query.Cache();

            GC.Collect();
            GC.WaitForPendingFinalizers();
            sw.Stop();

            var count = 0ul;
            result.Count().ToStreamEventObservable().ForEachAsync(r => count += r.Payload).Wait();
            Console.WriteLine("Query Took {0} ms on average, had {1} rows", sw.ElapsedMilliseconds / repeatCount, count);

Config:

{ MapArity = 2,
 ReduceArity = 2,
 ForceRowBasedExecution = False,
 DeterministicWithinTimestamp = True,
 ClearColumnsOnReturn = False,
 DisableMemoryPooling = False,
 DataBatchSize = 80000,
 UseMultiString = False,
 IngressSortingTechnique = ImpatienceSort,
 MultiStringTransforms = None,
 Scheduler = OwnedThreadsScheduler(Map:2, Reduce:2),
 GeneratedCodePath = Generated,
 GenerateDebugInfo = True,
 BreakIntoCodeGen = None,
 DontFallBackToRowBasedExecution = False,
 SuperStrictColumnar = False,
 CodeGenAfa = True }