Image rendering IO Error on Smartphone but not on Desktop

Hi Everyone, I am trying to figure out a bug on a program right now.

Basically this is just a test app, and there’s some sort of error.

I made an observable out of a wallpaper and have put it to the screen. It works just fine on Desktop testing (as shown), but when I am testing it to Android it says something is wrong and this is the specific error message:

ERROR: Couldn’t open file: Assets/wallpaper.jpg Uno.IO.IOException occured

The testing on Android phone made this error occured but it works just fine on desktop.

Screenshot of the whole desktop environment: (As you can see, it works just fine)

Screenshot of the mobile app: (Error occurs) file