State machine for a game object in Unity doesn't seem to be working. Instead of changing from "stagger" to "idle", it just keeps moving

So I'm developing my first game in Unity currently (following a series by Mister Taft on YouTube called "Make a game like Zelda using Unity and C#" and just finished the 19th video).

I've currently got a "Log" enemy and am working on a knockback feature. I've followed the way that it is approached in the series is by creating a state machine that changes the Log's state to "stagger" for a couple of seconds, then return it to "idle" so it can change itself to "walk."

Whenever I hit the Log, however, it gets stuck in the stagger state and drifts without stopping until it hits a collider (note it doesn't change back to idle/walk even when it does hit the collider). If I can hit the Log correctly, sometimes, the player will actually also drift in the opposite direction.

Relevant code:

public class Log : Enemy {

    private Rigidbody2D myRigidBody;
    public Transform target;
    public float chaseRadius;
    public float attackRadius;
    public Transform homePosition;
    public Animator anim;

    // Use this for initialization
    void Start () {
        currentState = EnemyState.idle;
        myRigidBody = GetComponent<Rigidbody2D> ();
        anim = GetComponent<Animator> ();
        target = GameObject.FindWithTag ("Player").transform;

    }
    
    // FixedUpdate is called by physics.
    void FixedUpdate () {
        CheckDistance ();
    }

    //Log finds and walks towards Player.
    void CheckDistance(){
        if (Vector3.Distance (target.position, transform.position) <= chaseRadius && Vector3.Distance (target.position, transform.position) > attackRadius
&& currentState != EnemyState.stagger) 
        {
            Vector3 temp = Vector3.MoveTowards (transform.position, target.position, moveSpeed * Time.deltaTime);
            myRigidBody.MovePosition (temp);
            ChangeState (EnemyState.walk);
        } 
    }

    private void ChangeState(EnemyState newState){
        if (currentState != newState) 
        {
            currentState = newState;
        
        }
    }
}

public class Knockback : MonoBehaviour {

    public float thrust;
    public float knockTime;

    private void OnTriggerEnter2D(Collider2D other){

        if (other.gameObject.CompareTag ("breakable")) 
        {
            other.GetComponent<Pot>().Smash();
        }

        if(other.gameObject.CompareTag("enemy"))
        {
            Rigidbody2D enemy = other.GetComponent<Rigidbody2D>();
            if (enemy != null) 
            {
                enemy.GetComponent<Enemy> ().currentState = EnemyState.stagger;
                Vector2 difference = enemy.transform.position - transform.position;
                difference = difference.normalized * thrust;
                enemy.AddForce (difference, ForceMode2D.Impulse);
                StartCoroutine (KnockCo (enemy));
            }
        }
    }

    private IEnumerator KnockCo(Rigidbody2D enemy){
        if (enemy != null) 
        {
            yield return new WaitForSeconds (knockTime);
            enemy.velocity = Vector2.zero;
            enemy.GetComponent<Enemy>().currentState = EnemyState.idle;
        }
    }
}

public enum EnemyState{
    idle,
    walk,
    attack,
    stagger
}

public class Enemy : MonoBehaviour {

    public EnemyState currentState;
    public int enemyHealth;
    public string enemyName;
    public int baseAttack;
    public float moveSpeed;
}

I've tried to add an else statement after the void CheckDistance in Log.cs, but that resulted in the Log having jittery movement and jumping back along its path. I'm at a loss. Any help would be greatly appreciated!