You're going to have to use a different angle on the "angle"......Maybe try a little skin holding or streching...
It could be that DE blades have a bit more flex than either SE or injector blades. Even at that, I can't imagine why a thicker/stiffer blade would cause bumps while DE blades don't, with all else presumably being equal.
I'm with Bird Lives: check the angle on the angle. Since the angle along the chin changes there quickly, you might try and use shorter strokes, each time checking the angle.
I recently use a GEM razor and found that skin stretching helped tons in some spots. Give that a try.
Same area I have problems in. Fortunately no irritation, just difficult at times getting it as smooth as I would like. And is there shame using a DE for touch up to get a shave you're happy with? Why does a carpenter have different hammers? Why does a chef have different knives? They know what tool is going to most efficiently get the job done. So I say, USE THE DE FOR THE FINISHING TOUCHES! THERE IS NO SHAME IN BBS!!
It seems like its going away by going VERY slow and changing my angle around the curvature carefully. I've got a Tech on the way just in case.