Yes, walnut gets into pockets. No, most carbide dies do not REQUIRE lube, but a little seems to make it much easier, and brass last longer. I use a smidge of alox spray on mine. Back in the day, we used to use a new ink stamp pad with no ink on it, put a few drops of lube on the pad, roll the brass by hand on the pad. Low tech, but it worked.
What we have here is... failure- to communicate.