Hey Hach. I haven't been able to play much MP or anything for that matter because my girl broke my PC. So this might have been fixed in the patch as I’m not sure. But I can say that in my experience onagers will move forward if the units they are to attack are out of their range and you order them to attack. If you place the onagers behind your troops they will push the units in front of them forward. So best to keep your onagers on either fire at will under they start to fire or wait unit you get the green arrow showing the unit they are to attack are in range. If you order them to attack before the green arrow they will mess up your formation. That might be the cause. I’d test it myself now but I can’t. Hopefully somebody else can help you out that can actually test it