How to reproduce:
1. Download project from OC "Case_1116007_TimelineAnimationPlayableAsset"
2. Open Timeline Window
3. Select "TimeLine" in the Hierarchy
4. Click on HumanoidWalk Animation Track in Timeline Window
5. In the Inspector, change position x value
6. Set position x value back to 0

Expected result: "Character" is in the same position compared to the starting position
Actual result: "Character" position is different from the starting position

Reproducible with - 2018.3.0b2, 2018.3.2f1, 2019.1.0a14
Not reproducible with - 2017.4.18f1, 2018.3.0b1

Notes:
1) This is not reproducible when Apply Root Motion is set to true in "Character" Animator
2) This bug only reproduces if Timeline Window is open
3) Changing any other value or parameter in the Inspector when HumanoidWalk Animation Track is selected also produces the issue.