Have you guys published the app in google play store, I usually face this type of errors when working with AdMob When I don't have any published apk on the store!
Or sometimes if you test the ads and clicks (many time) without enabling the test Ads features i.e using actual ads to check the game is working or not! Than google stops sending the ads to the device! Better use TestAds feature, also I have found that you can show test ads without even setting the ads IDs or Ad Account, they have provided some test Ads Ids to test with, Try putting them and test the app if they shows that means the ads are set correctly and working fine in your game, the problem is what i mention anyone of that!
just put these no need to set anything else! Let me know if they appears or not!
Ad format Sample ad unit ID
Banner ca-app-pub-3940256099942544/6300978111
Interstitial ca-app-pub-3940256099942544/1033173712
Interstitial Video ca-app-pub-3940256099942544/8691691433
Rewarded Video ca-app-pub-3940256099942544/5224354917
Native Advanced ca-app-pub-3940256099942544/2247696110
Native Advanced Video ca-app-pub-3940256099942544/1044960115
Here are the link for topic!
https://developers.google.com/admob/android/test-ads
TO ADD LOCATION PERMISSION
To add them, Open the extension and Click on Android (Bottom Right) and Than on + button right to "Android Permission:"
Add the following Without " ":
"android.permission.ACCESS_COARSE_LOCATION"
and
"android.permission.ACCESS_FINE_LOCATION"
It'll work! You can add anyone depending on the requirement of your ad provider!