When the SpeedRatio Property is used in a Storyboard, the animation speeds up to the set SpeedRatio multiplier. However, there is a mismatch between the playhead movement, the keyframe positions, and the playback.

This is manifested by seeing the playhead not travel across the duration of the timeline keyframes when previewing the Storyboard, making it appear as if the entire animation isn't playing (if only observing the timeline).

There are two potential solutions to correct this mismatch:

1) Adjusting the playhead behaviour so that it travels across the entire timeline (just as an accelerated or decelerated speed as dictated by the SpeedRatio)
2) Changing the position of the keyframes of an animation to reflect the Speed of playback. (so for example, compressing the distance between each keyframe in the case of a positive SpeedRatio)

To aid in "syncing up" multiple concurrent timelines that all run relative to the projects master timeline, as well as accounting for other Properties, such as BeginTime, we should likely opt for option 2).