I have implemented Admob banner ads inside my other android apps and I know the procedure to implement Admob banner ads. But now when I have a new Playstore account and new Admob account and I tried to implement Admob real live ads are not showing. It is showing blank but test ads are showing properly.
I had tried putting my other app's ad-id and it is showing ads.I have created the ad ids before 6 days and still, no live ads are shown.
I have experienced this issue before you need to update android studio and use latest versions of Google services and AdMob.
Also, try to not change the size of the banner