To reproduce:

1. Open the project, attached by the user (Star Wards.zip)
2. Open the "UI BUG" scene
3. In the Hierarchy, expand Game HUD -> Action Panel
4. Enable any one of the disabled children of Action Panel game object -> no buttons or other controls are rendered
5. Add new UI Button to the game object enabled in 4
6. Buttons are now rendered correctly

Expected: UI elements are rendered when the parent game object is enabled
Actual: UI elements are not rendered until some other UI element is added

Reproduced in 2017.2.0b2
Could not reproduce in any other version, because the project simply doesn't open