So the status you have added is the Approved one? If that is the case and this is the one that the process is stopping at, the only assigment that should be taking place is the one that has happened above the DSR Approval status. The one that occurs before the Build status shold not be processed until after you have executed the Schedule action.
Have I understood this correctly?
As is so very often the case, came in this morning, raised a new change and the problem has now disappeared.....