[Sequencer] Setting additive transform keyframes on Actor Blueprints (using S hotkey) causes Actor to pop

See attached gif for popping behavior. The issue does not occur if using the Enter hotkey or clicking the Add Keyframe button. The issue also does not occur on static or skeletal meshes. 

1. Create new Blueprint class derived from Actor
2. Add a mesh component or similar visual to the class to help visualize
3. Add actor to a level sequence
4. Add a transform track and keyframe a simple animation on the base section
5. Add an additive section
6. Create an initial additive keyframe (zero-key)
7. Scrub to a new time in Sequencer
8. Select and move the actor in the viewport, then press "S"
9. observe the actor pops as soon as the keyframe is created