for the latest 4.0 ver, when there's a image to cover a large portion of the working area (often as a reference image), the ghosting won't be showing on top of it, it can be only shown when you turn off that layer/slots, I'm not sure if its some kind of feature or just a bug, I figure on my own that Spine actually turns the whole screen of opaque/working pixels for the ghosting to show, thus when there's a static background image behind everything, Spine wouldn't know that there is something animating in front of it at all, if that's the case, will it be solved in the future?