how to paint Alpha8 sprite?

Hello! First of all, I'm sorry for my English ) The issue is simple I believe - I just don't get something. So I have a solid-colored sprite and I would like to use Alpha8 compression for that sprite. Also that sprite is inside an atlas. Then, I put that sprite as a source for an Image component. And then I want to paint that sprite into a red color, for example. And everything is fine in the Editor until I press Play button - sprite is black at runtime. So the question is how can I paint the Alpha8 compressed sprite? What shader should I use? Is there a problem in atlas?