The infantry showcase mission is hard to complete at the very end. At the very end of the mission there are 3 cars standing at the depot. You have to shoot them from far away and not come too closely as per mission objectives. I had to restart and redo the last chunk of the mission like 20 times. The depot alarms start ringing, then while you keep shooting at the cars below from some hill above the mission just fails for no reason. Either you are standing on the "wrong" hill or in the "wrong" location is not clear at all and it's VERY annoying.
For example it would be better for the mission objective to be more specific like "shoot at the enemy cars from at least 300 meters from any elevated area you can find" or something along these lines. Also make sure that's what the game engine checks exactly in this mission so shooting those targets from ANY hill and not just some specific hill that was not even clearly specified in the mission objective at all. Maybe to make it even simpler just let the player destroy the targets from any elevated or non-elevated terrain completely regardless of their actual position on the map as far as they were shooting from at least 300 meters and didn't come close to the enemy depot.