UnityAds not working on 2018.1.3f1

Hi everybody, I have an app that was published on July 2017 with UnityAds which used to work until we disabled them on February 2018 off because of low eCPM rates. We thought that was affecting to our purchases.

After many time we have reactivated them and the problem comes here. Everything appears to be working fine with the Live version of the application, but we have updated the project from Unity 2017.4.1f1 to Unity 2018.1.3f1.

A lot of things have changed in Unity from 2017 to 2018 and I don't know how can I test UnityAds right now.

In the past we configured a S2S - Callback like this; https://unityads.unity3d.com/help/monetization/s2s-redeem-callbacks, in order to verify that the video has been correctly watched.

Right now I'm watching ads, but this callback is never called. ¿Am I doing something wrong?

Code (CSharp):

1. public void ShowRewardedAd()
2.     {
3.         ShowOptions options;
4.  
5.         options = new ShowOptions
6.         {
7.             gamerSid = _gamerSid,
8.             resultCallback = HandleShowResult
9.         };
10.  
11.         Advertisement.Show("rewardedVideo", options);
12.     }

Where the _gamerSid is the ID of the test Device.

I'm getting a ShowResult.Finished as a response, so the video is correctly shown.

I don't know what I'm doing wrong.

Btw I've updated UnityAds via PackageManager.

I expect that any of you can help me.

Greetings,
Nacho.