Trouble with button's On Click () on a real Android device

I have a Canvas and a parent that contains some objects with the Button component attached to them. OnClick function is adjusted so all the buttons work fine in Unity. When I run it on a real device through USB all these buttons react to touches by changing the state to Selected but do not work as buttons. The problem occures only when the buttons have a parent in Canvas hierarchy except Canvas itself. For example if I have the buttons only as children for Canvas the app works fine on Android phone as well. So what does it mean? It's a bug or I have some wrong build settings or it's just such a unique phone which I have?