Hi Florin,
Thank you for providing the Ad Unit Id in question privately.
I tested your Ad Unit Id with our
HelloWorld sample app and I was able to load and show an Interstitial App Install Ad that redirects to the "Cars Puzzle Game" which I assume is the house ad that you are referring to. You may watch
this video recording of my testing for your reference.
That said, we can safely assume that the issue is specific to serving of your house ad rather than anything specific to the Mobile Ads SDK because you mentioned you are able to load other ads on your end. It's possible that on your end, the ads that are being pulled are from the AdMob Network instead of your house ad campaign.