So maybe I'm missing something. After the update that added those custom icons, I was under the impression we would be able to manually select which class icon each soldier had at some point. I'm half way through a fresh game I started after said update, and I don't see any option to do so.

Class icon still gets changed based on perk selection, which I find rather annoying. I can pick, say, three perks from the Infantry class, making the character an Infantry class...but if I pick something like the Ammo slot perk from Gunner (or whatever class it's from), it changes my class to that. It really feels random and is super hard to control.

In that same situation, let's say I have one perk in Grenadier and one perk in Sniper. So I take the second perk of Grenadier which turns me into a Grenadier, and then the second perk in Sniper which turns me into a Sniper...but if I reverse the choice, taking Sniper first and Grenadier second, I remain a Sniper. Just using hypothetical classes and perks here to make a point. There doesn't seem to be any rhyme or reason to the class change when selecting perks.