How do I implement Google Admobs Interstitial Ads Successfully?

Hi, I am working on a mobile game using UE4 and I am going through a very annoying problem.
I can’t for the life of me figure out a way to put an interstitial Ad into my blueprint written mobile game.
I have tried to use the Interstitial Ad Unit Test ID shown in the link (Enabling test ads  |  Android  |  Google Developers), but I am getting no output at all when using Load Interstitial Ad and Show Interstitial Ad.

Banner Test ID seems to be working but the Interstitial Ad Test ID is not giving off any output to the screen, and this was all done AFTER packaging the project onto the mobile phone.
Funny thing is, UE4 seems to have inbuilt default nodes for Interstitial Ads but none of them seem to be working and the lack of tutorials on how to get it working is shocking.

Can someone help point me in the right direction? or atleast clarify if Interstitial Ads ARE SUPPORTED for ue4.17.2 or not?

Many Thanks

if you find it tell me too im in the same spot