its definitely random. trying many things right now. Will update if i have any sucess

@DancesWithDingo From my experiments the z-index of annotations is determined by their latitude value. The lower the value, the higher the z-index. So, for example. This: CLLocationCoordinate2D(latitude: 37.66183, longitude: -122.37757 will overlap this: CLLocationCoordinate2D(latitude: 37.736555, longitude: -122.256918