I was not scrubbing through the cinematic just pressing “play / simulate” then pressing play on the cinematic it would run with simulation continuing to play. In 4.14+ it disconnects the camera and returns the view to the starting point of the camera. I would have the view port tied to the camera of the cinematic to be played, for instance I have 3 in one scene and if I just attached the camera, then stopped and started the sim then play on the cinematic it would keep the camera attached to the view port and play. This is really nice when using the Ocean plugin or any scene with physics going off so you can test it will out running the game, very good for fine tuning.
I am streaming right now if you want I can repro it for you live on both versions of the level 4.12.5 and 4.14. twitch.tv/vexarax let me know if you are there I will drop what I am doing and show it.