Project Steps:

1. Open project (Attached by HingeBug).
2. Play scene "5.0 Test".
3. Select game object "Cube", to analyse changes.
4. Press "D" (it should chnage hinge target position).
5. Notice that nothing happens.
6. Stop playing scene.
7. Open script "RightFlipperScript".
8. Uncomment 36 and 37 lines.
9. Play scene "5.0 Test".
10. Press "D".
11. Everything works fine.

Workaround:

- Check if connected rigid body sleeping, then wake up it.

Reproduced: 5.0.1f1, 5.0.0p3, 5.0.0b22, 5.0.0b15, 5.0.0b10
Regression: 4*