Ad Manager does not show ads

Kreator Camp Ad Manager
1

I have an app with ad manager banner and interstitial. The test mode is unchecked in both. When I publish my APK , no ads are shown. Does anyone why Ada are not shown???
I have app-ads.txt published and my ad manager account does not give any error.

When I check the ads with test mode in companion, these are shown perfectly.

2

Same things happen to me, in test mode ads were shown perfectly but after publishing on play Store no any ads are visible. My account is approved also.

3

This may probably be due to a low ad fill rate. But I don´t know sure.