12 point or 6 point socket or box end wrench fitting a nut

[dmjlambert]

OK here is something I have not encountered before in decades of mechanical work. I can't figure out how this is possible.

I am trying to adjust a 71-72 tie rod and the clamp bolt and nut are 1/2 inch. The bolt and nut both fit a 1/2 inch open end wrench just great. I have Craftsman combination wrenches with a 12 point box end, and a couple brands of ratcheting box end wrenches with 12 points, and 12 and 6 point sockets. Nothing I have that is 12 point will fit onto the nut at all, that includes box end wrenches regular and ratcheting and 12 point sockets. The 6 point socket just slides right on the nut with no problem. The open end wrench will fit on the nut with no problem, fitting on any pair of the 6 sides. The bolt head is the same size and and will work with 12 point or 6 point tools. The nut will absolutely not work with 12 point tools. I checked both clamp bolts on both sides of the truck, same story. The nuts appear to me to be high quality, other than the nuts don't work with 12 point tools. Is there something about that nut that makes it specially designed to not work with 12 point tools? I see a little bit of a ridge on a couple sides of the 6 sides. Is this nuts or am I a squirrel?

Unfortunately I don't remember the brand of tie rods. I got them from Manes Truck Parts and didn't keep the boxes.