Reproduction steps:
1. Open the attached project "CanvasTest.zip";
2. Open the only scene;
3. Enter a play mode;
4. Open the Profiler window if it is not opened;
5. In the scene view, simply try to move Canvas object under ParentObject;
6. Observe that CanvasRenderer.onTransformChanged is called only for one frame;
7. In the scene view, try to move ParentObject;
8. Observe that CanvasRenderer.onTransformChanged is called for every frame.

Reproduced on: 5.6.0b8, 5.5.1f1, 5.5.0f3;
Not reproduced on: 5.4.4p3 (due to errors).