sideOutputLateData not propagating late reports once window expires

[Slotterback, Chris]

Hey Flink Users,

I am having some issues with getting sideOutputLateData to properly function 
with late event time reports. I have the following code that, per my 
understanding, should be allowing reports that fall after the window has 
triggered and beyond allowed lateness to pass through to the side output:


val lateTag = new OutputTag[…]("tag"){}

val windowedStream = stream
  .keyBy(…)
  .window(TumblingEventTimeWindows.of(…))
  .allowedLateness(…)
  .sideOutputLateData(lateTag)
  .trigger(new myTrigger)
  .aggregate(new VSGBondingGroupMediansAggregator(packetFilterCount))


val lateStream =
  windowedStream.getSideOutput(lateTag);


trigger:

public class myTrigger extends Trigger<…>, Window> {
    @Override
    public TriggerResult onElement(…) throws Exception {
        return TriggerResult.CONTINUE;
    }

    @Override
    public TriggerResult onProcessingTime(…) throws Exception {
        throw new Exception("processing time not supported");
    }

    @Override
    public TriggerResult onEventTime(…) throws Exception {
        return TriggerResult.FIRE_AND_PURGE;
    }

The main flow is functional when all reports are ontime, but when I start 
introducing late reports, they get rejected by the window but are failing to 
end up in the late stream. Is there something off with my understanding?

Chris