Unity ADInterstitialAd instantly triggers iOS memory warning

I've been using the Unity built-in Ad Banner for iOS with no issues of any kind.

Recently I started incorporating Unity's ADInterstitialAd and as soon as I display even one Interstitial Ad, I get a memory warning in XCode. It dosen't seem to matter when or where I show the ad. I even tried to move it to the small level select screen and show the Interstitial Ad right before I load the main game screen and I still get the memory warning.

Then, as I test the stability of my code and go back and forth, I continue to get the memory warning each and every time until my game is killed because of iOS memory pressure.

I am not using any 3rd party plug-ins.

Please help.

Thanks, Manny