I have a playable clip which iterates through a list of sprites changing the image of a canvas to do some animation, in play mode takes however long the clip length is and works great. However, in editor mode pressing the play on timeline by time the header is 50% of the way through the clip, the animation has finished.
The clip is 120 frames
play mode: finishes at 120 frames
editor mode: finishes at approx 60 frames
Unity version is 2017.3.0b6