Steps to reproduce:
1. Open user attached project
2. Find the StrikeView prefab in the project, drag it on the canvas
3. Notice that the ball is not in the middle even though it should be
4. Click revert - the ball goes back to the center
5. Click apply
6. Delete the prefab game object and drag it back it on the canvas
7. Notice that the center position is not saved

Expected result: UI prefab position should be applied and saved

Reproduced in: 2018.1.0b1, 2017.3.0f3, 2017.3.0f1
Not reproduced in: 2017.3.0b11, 2017.2.1p1
Regression since: 2017.3.0f1

Fixed in: 2018.2.0b10