My forces will not follow enemy forces when set to attack.

[Garrison]

I noticed this in mission 7 when planes started attacking my base. I could tell a small squadron of my planes to attack the enemy which they would but the enemy was moving all over my base. My planes would not automatically follow them. That means I had to keep moving them. I had given them an order directed at the planes so the red lines appeared but they still don't follow. That means I had to coordinate the entire defense until the attack was over preventing me from concentrating on anything else. Is there a possibility this could be changed or am I doing something wrong? Also is there a way to select more than one enemy at once so that when they finish attacking one enemy in a group they will move on to the next? Thanks.