While not necessarily a balance issue I find the new squad formations and garrison mechanics pretty frustrating from time to time with every faction and is probably the number one thing that tilts me ingame.
NUMBER 5 Your close quarters units refusing to fight close quarters because there is some yellow cover nearby so they snap to it like magnets while you are trying to close ground on the enemy. It is very annoying to rush Sturms into a squad just to have them turn around and move back 5 meters cause a stick is on the ground.