Game behavior changes from Unity editor when transferred to Phone(apk).

I am working on a game in unity that I am supposed to publish on Google play store and app store ,but at the last stage I am encountering an error, I don't know what kind of error this is but I can elaborate it.

So I made a game in unity 2018.2.2 , it was completed and everything was working fine in editor as well the APK , I even uploaded it in google play console for internal test and rollout , but I saw a warning which said something like :" scripting back-end should be "IL2CPP" .

So, I went to my unity editor and changed the scripting back-end in player setting from "MONO" to " IL2CPP" and tried to build and received " IL2CPP linker error" , I updated my unity from 2018.2.2 to unity 2019.1.4 recently after officially receiving a response from Unity to update the player after submitting a bug report.

Now when I build with scripting back-end "IL2CPP" , it does build the APK but , when I run the APK on my phone the game's functionality is unstable. The GAME BEHAVIOUR HAS CHANGED.

The score counter(top right) in the game scene doesn't change when I press Spin button. Also you can see the reels are getting disappeared . But it works perfectly fine in the editor, everything does! .

Attached are the small videos of the Gameplay on Both the Unity Editor and the Phone as a Google Drive Link. Please Help me out!!! . Thanks!.

GOOGLE DRIVE: https://drive.google.com/open?id=1NpnhL1tkOh4sBPPhm92W0F8q1gFVenU3

 

Is there a reason you went to the latest tech release, instead of the latest 2018.4 LTS version for a completed project?