I am actually having a very similar problem, but I have a few suggestions just in case the cause of your problem is different. Depending on whether it is a software/firmware issue, or a hardware issue (clogging, jamming etc.), the solution will be different. Are you able to take the hot end off so that you can extrude filament and have no interferance from the hot end or any other parts? I think I have a test you can try to tell which kind of issue it is.