Unity 2017.3.1 simple android app blank screen between splashscreen and scene-0

I am using Unity 2017.3.1 and Vuforia 7.0.47 and a sample app with loading screen. I exported this Android code and used UnityPlayer to merge inside part of my Android app.

As I have purchased Unity Plus license,I added custom Splashscreen,build and Run from Unity on Android mobile,app works fine without any blankscreen before scene 0.But If I export the code and copy assets on Android app,then blank screen shows for around 15 seconds in between Splashscreen(Shows 2 secs) and Scene 0.

There is no lot of objects in Scene-0.Just empty scene with canvas and Loading text.