Okay, I looked into this more. The DLC cache has the correct icons for all the ones I see. I'm not sure why something bugged out when copying some of them, but it appears to be working now. Sorry for wasting any time you spent.
As the title says. A handful of tanks (IS-3, Leopard 1 I've noticed in game, others in files) have a different contour icon style than the rest. I believe it is the default Aslain's style. Here is a screenshot showing some of the bugged icons.