Steps to reproduce:
1. Open attached “CurveEdit.zip” Unity project
2. Open “Test” scene
3. Select “Director” object in Hierarchy
4. Go to Window->Timeline Editor
5. Position timeline playhead to the middle of “LightControlClip” clip
6. Change the middle curve key value to change the light intensity

Expected results:
Changes in curve editor are applied immediately and are visible in scene
Actual results:
Changes in curve editor are not applied immediately and changes are not visible in scene

Reproduced in: 2018.1.0a7, 2017.3.0f2, 2017.2.1f1, 2017.1.2p4, 2017.1.0f3

Note: Changes are applied only after muting and unmuting track or reselecting Playable Director object in Hierarchy