What does this icon mean in AndroidStudio?

Question

Android

These are the icons that appear in AndroidStudio when background is set via drawable.
What is it connected with?
What am I doing wrong?

composition of round_avatar:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="oval">
            <solid android:color="@color/avatar_bg" />
        </shape>
    </item>
</selector>

Answer 1

This is not a bug in your code. It's just that the studio couldn't show a preview of the picture.

Answer 2

Hover your mouse over the icon, wait for the tooltip - and find out.