I, too, have the same problem, and the button to add default code puts in default code, all right, but that code doesn't work. It looks like it ought to work, but it doesn't. I also tried putting in the default start code from Slic3r, but that only works for Slic3r, not Cura. This is either a persistent bug in Repetier Host, or a bug in Cura slicer, or it's just a feature that is totally not easy to figure out. Any ideas how to narrow down the problem?