Android app closes after unity ad finished?

Hello, I'm facing a weird problem. I created an android app and I'm using Unity ads in it. I successfully implemented the banner ad without any problem in my app. I also implemented the Interstitial ad in my app. But the problem is when I am closing the ad (Interstitial) after it finishes, my app closes (not crashing though).

I used logging to see where it is happening. I found that it was happening when the onUnityAdsFinish() is called.

Please help me here!

NOTE: In the latest build of Unity-ads.aar file doesn't have the IUnityAdsListener (must be included) interface. I have to download the previous one for that.