Infantry wandering about after orders, Attack-move is your friend, you should be using A-move more than attack, you shouldn't really be clicking on units most of the time anyway, I understand sometimes you need to focus fire a setting-up MG from time to time though. It's all due to dodgy LoS blockers so make sure you have clear line of sight before issuing direct attack orders.
1) Load up a map with CHEATMODS.
2) Make a set of enemy pios.
3) Give your REs the rifle grenade upgrade.
4) Move REs just to the FOW where they CAN see the enemy.
5) Select the REs and then focus fire the pios.
Your REs will walk over to the Pios. Stand there for a second. Then walk around the pios. Then maybe start engaging if your still alive.
This is the behavior I see in game. I see this in many games with many units. Sometimes tanks even do it. Like they just cant see the enemy. Sometimes my units will start attacking for 1-2 seconds then move up a few meters and start attacking again. Even though they are only 10 meters away to begin with. It is like they kill the closest model then CANT SEE the enemy anymore.
I used to say its the server, but then why is my game drawing the enemy units correctly?
United States

Lion king
Private Mok
보드카 중대
Heartless Jäger