Admob ads not showing on android real device (react-native-firebase)

I am using react-native-firebase admob feature on my app.

Set up interstital and banner ads both, not published the new update with ads on appstore or playstore yet, just testing now.

Followed exact installation steps here

On iOS, both test ads and real ads (on real device) working fine. Even earning!

On android; test ads and real ads working good on emulator. But on real device (with release-apk) non of them works.

1. Payment options ok (already earning from ios)
2. Account verified
3. Test ads are working perfectly fine
4. Without test ads (with real ad unit id) it shows real ads on emulator
5. Have been 10 days since i created ad units
6. I can see 30 requests on admob, no impression. Probably from real ads on emulator. So can communicate with admob

But now showing ads on real device with release apk. What might be the problem ?

If anyone did all same things above and got the same problem like me,here how I solved it:

Just publish it on playstore and admob starts working.