Why is my Unity Ads Fill Rate at 0%?

Hi Unity Answers,

Last night my first game went live. My game makes all of its money through Unity Ad interstitials. When I first implemented the Unity Ads, they worked perfect on my device, but while the game was in review with Apple, the ads stopped showing. Now, on the release build, no ads display. When I go to my dashboard on the unityads.unity3d.com site, it says my fill rate is 0%. Do you know why this is happening?

I tried playing the build in the Unity Editor, and the ads seem to be called correctly, I get the blue screens saying that my ad calls are working fine, and when I run the build in Xcode, I can clearly see that the calls are being made. Is there a reason that my fill rate would be 0%? And will it go back up to something larger? I am incredibly new to this, and I think you soooooo much for your help!

Thanks,

Sean