Steps to reproduce:

1. Download and import attached project.
2. Load "scene" scene.
3. Select "Main Camera"
4. Change "My Property Field" value to any you like.
5. Save the scene.
6. Close Unity and open it again, notice that "My Property Field" did not changed.

Expected result: "My Property Field" value change is successfully saved in the scene.
Actual result: "My Property Field" value changes are not saved.

Reproduced: 5.3.0f3, 5.3.0f2, 5.3.0b1
Did not reproduced: 5.2.2f1, 5.1.4f1

Regression starts on: 5.3.0b1