I have a point feature service in AGOL that I want to show as active or inactive based on whether or not there is a date value. When features are created the values are null. Essentially I want to show null as one color and not null as another. I was able to accomplish this by using Types (Unique Symbol) based on a Custom Expression using IsEmpty(). It works in my AGOL web map, but not in Collector. There is no point symbology in Collector. I can add a new point, but it doesn't display. I assume this isn't supported, but why? Is there another way to go about this? Is there a way to determine what can be done in AGOL that isn't supported in Collector or Explorer?