Why the ping pong is not working on the waypoints?

Your editor freezes because in the case that pingPongEnabled is set to true you do

if (pingPongEnabled)
{
    transform.position = Vector3.MoveTowards(pingPongStart, WayPoints[CurrentWayPoint].transform.position, Mathf.PingPong(Time.time * 1, 1) * Time.deltaTime);
    continue;
}

without yielding within the loop -> due to continue it immediately goes to the next iteration without the exit condition ever fulfilled.

You want to make sure to always do

if (pingPongEnabled)
{
    transform.position = Vector3.MoveTowards(pingPongStart, WayPoints[CurrentWayPoint].transform.position, Mathf.PingPong(Time.time * 1, 1) * Time.deltaTime);     
    yield return null;
    continue;
}

in order to at least wait until the next frame with the next iteration

Anyway, this

transform.position = Vector3.MoveTowards(pingPongStart, WayPoints[CurrentWayPoint].transform.position, Mathf.PingPong(Time.time * 1, 1) * Time.deltaTime);

doesn't really "ping-pong" like you would probably expect. It always starts back at pingPongStart and moves a single step towards the waypoint and only goes a bit further or less.

You probably rather ment

transform.position = Vector3.Lerp(pingPongStart, WayPoints[CurrentWayPoint].transform.position, Mathf.PingPong(Time.time, 1));