Unit rotation fails consistently on all slerp rotations after the first?

I'm working on a small project where my units need to move around on a 2D board, facing their movement directions before they do.

I've got it to a point where the first time someone clicks on the map, the unit rotates smoothly towards the target and then moves. However, after that - all subsequent rotations only rotate a portion of the way. I'm not sure what if anything is wrong with my code to cause that.

It takes place in a coroutine, and while loop. Here is a visual example:

This is the code I have thus far. It's possible that I'm not resetting something, but I'm not sure what as most of the variables are self-contained.

 public Transform _transform;
 public Vector3 CurrentTarget;

 public Quaternion TargetRotation;

 private bool canMove = true;
 private bool isRotating = false;

 public float lerpDurationTime = 2f;

 // Start is called before the first frame update
 void Start()
 {
     _transform = transform;
 }


 public void Move(Vector3 TargetPosition)
 {
     if (canMove) {

         if (CurrentTarget != TargetPosition) {
             CurrentTarget = TargetPosition;
         }
         
         if (LookingAtTarget(CurrentTarget)) {
             Tween.Position(_transform, CurrentTarget, 2, 0, Tween.EaseLinear, Tween.LoopType.None, null, () => {
                 canMove = true;
             });

             canMove = false;
         } else {
             TargetRotation = Quaternion.LookRotation(-CurrentTarget - _transform.position, Vector3.up);
             StartCoroutine(LerpRotation(2));
         }
     }
 }

 IEnumerator LerpRotation(float duration)
 {
     float time = 0;
     Quaternion startValue = transform.rotation;

     while (time < duration) {
         transform.rotation = Quaternion.Slerp(startValue, TargetRotation, time / duration);
         time += Time.deltaTime;
         yield return null;
     }
     transform.rotation = TargetRotation;
     Move(CurrentTarget);
 }

 private bool LookingAtTarget(Vector3 target)
 {
     float angle = 5;

     if (Vector3.Angle(-_transform.forward, target - _transform.position) < angle) {
         return true;
     }

     return false;
 }