Texture Coloring app run in the Unity Editor well, but does not working in the device for imported modules in Unity version 2020.1.0f1.

I have developed a simple coloring application in Unity3d (2020.1.0f1). Basically what it does is based on the touch, it identifies the touched object and changes the texture color of the touched object using flood fill algorithm. That worked fine in the Unity editor mode. But when I run that application in both Android and IOS devices, the coloring did not work for imported objects. It only worked for unity built-in objects. After that, I used Unity 2018.4.20f1 for building that application. Then that application worked fine on the mobile device. But I want to use the 2020.1.0f1 version because there are some features that I want but not included in the 2018.4.20f1 version. Can anyone help me to find a solution for this problem?