AdMob ads in one of my apps have been showing normally for the first 1.5 days after being published on Google Play. However, all of a sudden, ads stop showing, which occurred in all 3 devices available to me. I did not update the app on Google Play during this period.
Logcat in Android Studio shows "Ad failed to load : 3", which means ERROR_CODE_NO_FILL. However, there are no current issues in my AdMob Policy center, and the "no fill" situation has been present for 10+ hours.
What should I do next?