It is no secret that MDT 2013 Update 1 had more than one problem:
MDT 2013 Update 1 Release Notes and Known Issues
Microsoft has now updated MDT 2013 Update 1 to build 8298 and fixed some of the problem but as you can read here there are still known issues:
MDT 2013 Update 1 re-released (build 8298)
You can download the new build here: