I'm using the "cluster" featureReduction in JSAPI 4.15 against a hosted featurelayer with ~750K points. I have a popup configured on the clustered layer using the cluster_count variable. This works fine in most of the cases, but there are a few examples where clicking on the cluster produces no popup - it's like the feature isn't there. I can't find a pattern to explain why some clusters respond to the click and others don't. Can someone please help me?