No ADS view in IOS app.

I can not see any ads in the editor to test it.
I have this code in other older apps without any problems.

Unity Version 5.6.1f1

using UnityEngine;
using UnityEngine.Advertisements;
public class ads : MonoBehaviour
{
void Start ()
{
if (Advertisement.IsReady())
{
Advertisement.Show();
}
}
}

I have done a project with only 2 simple scenes. If i click on a button, i move to the next scene. With the code above all works fine with advertising.

So, maybe there are some issues with asset store plugins?

It usually takes a few seconds (depending on networking and traffic) to download the ads after they initialise. IsReady() will return false until ads have been downloaded.

Use:

IEnumerator Start() {
while (!Advertisement.IsReady()) yield return null;
Advertisement.Show();
}