Works fine on 5.0 and 5.2;

Opening project with 5.1, UI elements are not rendered in Scene view, though Game view renders UI elements as expected;

Repro steps:
1. open project "Tap Match.zip" with 5.1 version. In order to render UI elements "override sorting" option has to be selected for every nested canvas;
2. open the same project on 5.2. Scene and Game views works normally, no need to use "override sorting" option in nested canvases;