NavMesh Lookat causes jittery glitch in character

Quick Video: https://www.youtube.com/watch?v=xelPUNeJafM

Hi I'm updating my enemy destination and Lookat rotation every .25 seconds to follow the player. but the LookAT function is causing the enemy to glitch and move up for a frame... any ideas on a fix or workaround?

When I remove the lookat code it doesn't glitch.

Code:

IEnumerator checkdist()

 {
     dist = Vector3.Distance(player.transform.position, this.transform.position);
     while (dist>10.5f)
     {
         nav.transform.LookAt(player.transform.position);
         nav.SetDestination(player.transform.position);
         dist = Vector3.Distance(player.transform.position, this.transform.position);
         yield return new WaitForSeconds(.25f);
     }
     print("attack");
     StartCoroutine(hurtplayer());
     nav.speed = 0;
     yield return null;
 }