I believe this is because when there are few markers, all animations have completed by the start of the second iteration. This means there are no updates being rendered, so the postrender callback doesn't execute. May not be a problem as there are likely to be more than four moderate severity incidents during any given wet period. If we zoom in on a marker, we could possibly hide the rest so the animation continues unseen to keep the rendering going.
I believe this is because when there are few markers, all animations have completed by the start of the second iteration. This means there are no updates being rendered, so the postrender callback doesn't execute. May not be a problem as there are likely to be more than four moderate severity incidents during any given wet period. If we zoom in on a marker, we could possibly hide the rest so the animation continues unseen to keep the rendering going.