It should go back to it's default position because that's the intention of KJ's turret utility. It's not meant to remain locked on the position where the enemy was last seen. The turret regardless would not immediately switch targets mid burst.
Here's an explanation
https://twitter.com/NP01user/status/1569814904898736131?s=20&t=kJDwbjvQVX_0Z59B3Ej0_w