Yea, the code you gave works. The snippet I sent above is of the AITanks main body. In the picture I sent of the game, it rotates fine for a while, then all of a sudden, it starts to move at me at an angle.
In the attached picture is the Behavior Tree. What happens is I have a service that checks to see if the player is within a certain angle of the forward vector of the aitank. If so, I do a ray cast and check to make sure that what its hitting is the player and not a wall or something. If that all works, it sets a variable to combat which starts a task that rotates/moves the tank to the player as seen in the above snippet. However, I have noticed, that when I get out of the tanks cone of vision, it sets the variable to idle just fine, but in the BT it still stays in the combat selector. Thats where I think the problem is.