recently google made an announcement that they will no longer show ads to sdk less than 7.0.0 . What version of admob SDK does buildbox has?
For BB 2.2.8: Admob iOS to 7.14.0 (stand alone) https://www.buildbox.com/forum/index.php?threads/buildbox-2-2-8-beta-is-available.8301/ The latest version is 7.26.0 https://developers.google.com/admob/ios/download