TipUIPopoverViewController's imageSize doesn't work

Per the apple API documentation (https://developer.apple.com/documentation/tipkit/tipuipopoverviewcontroller/imagesize), imageSize is meant to control the size of the image within the tip, but it doesn't seem to be working. My code is as follows, taken from the apple docs example:

tipObservationTask = tipObservationTask ?? Task { @MainActor [weak controller] in
            for await shouldDisplay in tip.shouldDisplayUpdates {
                if shouldDisplay {
                    let popoverController = TipUIPopoverViewController(tip, sourceItem: sourceItem)
                    popoverController.imageSize = CGSize(width: 10, height: 10)
                    controller?.present(popoverController, animated: true)
                    tipPopoverController = popoverController
                } else {
                    if controller?.presentedViewController is TipUIPopoverViewController {
                        controller?.dismiss(animated: true)
                        tipPopoverController = nil
                    }
                }
            }
        }