I’ve noticed that if the enemy is on even a slight elevation difference (like half my own hitbox), Cone of Cold completely misses. Not resisted, just misses entirely. And this is with 2/2 Arctic Reach.
It seems like Cone of Cold also has a smaller horizontal range (not forward, but side to side) than I am used to in vanilla. In general I am pretty sure that this spell has a much more narrow cone effect range than was in vanilla, as I have to be far more accurate (facing the enemy directly) in order for this spell to hit them. This was not the case in vanilla.