Animation does not update in realtime as keys are moved in Additive Layer Tracks

This is a regression from 4.13

1. Open QAGame in the editor
2. Open the Run_AdditiveTracks animation in Persona
3. Scroll down the Additive Tracks until the pelvis(R) track is visible
4. Pause the animation and drag the timeline over the first set of keys in the pelvis(R) track
5. Select one of the keys and move it up and down

Result: Animation does not update until the key is let go

Expected: The animation should update as the user moves the key