Controlling Niagara with Sequencer not working


I have created a large scale cinematic effect in Niagara that I want to record with some interesting camera movements. For that I would need to be able to control the particle system in Sequencer to properly time the camera and make sure the two are in sync. Shaun Kime mentioned a while ago that this is possible by setting the variable namespace to user. I did that, the variable appears in Sequencer and it works when Sequencer is open and scrubbing on the timeline but it does nothing when in play or recording a video. Am I missing something or is this a bug?