Universal Mobile Ads for iOS & Android

Hi , today or yesterday our game suddenly started to show black screen instead of interstitial ads in iOS. Could you please check our game: Skate & Strike. Just launch Linear map, fail 3 times and it will show an interstitial. It was working just fine 2 days ago. Did AdMob change something maybe?

We are using Unreal Engine 4.20.

Edit: Only occurs in my iPhone 6.

Edit 2: Can’t reproduce anymore.