Some UI button script not working in apk build!

There are a lot of posts regarding this problem in various website and even in this one but no one has given a feasible solution to this problem. I have a button that has a custom sprite. I also have a custom script attached to that button which when pressed down (IPOINTER DOWN) changes the color of particular sprite renderer. All this works in pc but not on apk build. Why? I have two canvas, so I thought there might be raycasting issues, so I disabled one but still no luck. The buttons are in world space in canvas. So, I thought I might not use a canvas but IPointer only works on clickable UI elements.