Hello AdMob developers,
We uncovered a bug where ad requests from test devices registered through the AdMob UI always return no fill. This bug affects both Android and iOS ad requests.
We expect to push a fix in early December, and will update this thread when the fix is pushed out. In the meantime, the recommended workaround to get test ads is to remove your test device from the AdMob UI and add your test device programmatically.
Thanks,
Eric, Mobile Ads SDK Team