To reproduce:
1. Open attached project (Test.unitypackage);
2. Open "test" scene;
3. Enter Play mode;
4. Choose "Canvas2" game object, notice(in the Console and Inspectors Debug Mode) that Render Mode is the same: World Space;
5. Make "Canvas2" a child object of "Canvas";
-note that "Canvas2" should inherit "Canvas" Render Mode;
6. Compare Render Mode in the Console and Inspector.

Expected result: Render Mode is changed in the Inspector when making "Canvas2" Child Object of "Canvas".
Actual result: In the Inspector (Debug Mode), Render Mode of "Canvas2" remains the same it was before making it Child Object of another Canvas.

Reproduced on versions: 5.4.5p2, 5.5.3p2, 5.6.0p3, 2017.1.0b2.