Picture upload is not working in android webview app

I am developing android app with webview tool. I just showing url in app. That url site is developed in nopcommerce 4.0, product picture upload features is not working in my android webview app, but it properly working in website. It is default nopcommerce 4.0 site. I didn't change anything in code.

Hi, I was also searching solution for the same problem. After a long search I got a blog that has complete webview app development series videos, pictures, text tutorials guidelines and codes. I did just copy and paste and follow the guidelines and my website automatically turns into awesome apps. you can check it out if you wish.
Android Webview