Driving Blueprint FX via Sequencer without entering PIE mode

I am using a mask dissolve effect from here

I am also creating a Cinematic, not a game so everything is driven from my Level Sequencer.

I am able to trigger particle effects from my Sequencer but cannot get this effect to work unless I use PIE or SIE modes.
ie simply animating the mask fx cube from the Sequencer does not enable the effect. I must enter PIE mode.

The attached clips should make this a bit more clear.

1 Manually dragging mask fx cube in editor (Construction Script)

2 PIE mode animating mask fx cube (Event Tick in Event Graph)

3 animating mask fx cube via Sequencer (no PIE mode)

Can any Blueprint experts help? Can this type of effect be done without entering PIE mode?