Ok, I made few tests and I did not see any issues you are saying.
I launched P47 onto KT and drive with it just next to red circle.
Results?
P47s (after first wave when they attacked KT) were circling just next to KT which was out of the red circle by a hair.
No matter how many times I try, P47s always stop to attack when out of red circle (unless they target you for second wave before you ge of from the circle)
