Animation curves for material control

I’ve been following the steps of this tutorial

to animate a material on a skeletal mesh: I created the track, named it exactly as a scalar parameter in the material, turned on the material checkbox, assigned a material instance to the mesh. Yet the animation curve does not do anything.

The screenshots in that article look quite old so I’m not sure if the info there is up to date. Sadly the docs about animation sequences (Animation Sequence Editor | Unreal Engine Documentation) does not detail the use of animation curves.

Oh so the curve has no effect in the animation preview viewport but does work in game. Is not working in persona a bug?