Problems implementing AdMob AppOpen Ads in SwiftUI

I already implemented AdMob ads (Interstitial and AppOpen) in my Objective-C IOS App.
I was able also to implement the Banner ad my new SwiftUI App, but when I follow the rare online videos or posts on SwiftUI Ad Mob App Open ads, it does nothing (the ad does not display).
Was someone able to make it work and has an example to give me?