CircleSurface doesn't work with RayInteractable (Bug?)

I'm trying to setup a Canvas with a circular Image as a RayInteractable (RayInteractable component sits on the root "RayHoverSelectable" GameObject) but when I assign the CircleSurface in the Surface field of the RayInteractable, it detects it as a rectangular surface, instead of a circular surface (I can see this when I hover over the Image with my ControllerRayInteractor). The hover and unhover events do get fired so the rest of the setup works. Is this a bug or intended behaviour?