This seems to happen only with the first dock, so what I did was move the dock to a location on my desktop I don't really use for anything. I left it empty and made everything transparent so I don't have to look at it. So far so good, no more maddening empty icon. I still do hope this gets fixed though, as it is my favorite dock and I use it all the time! (If this has been posted before I apologize, it didn't come up in my research)
