Using Note Expression

I have a Hi-Hat track/lane that I am trying to apply note expression tuning to. In the key editor I select all the notes, open up the note expression window and draw my curve for the tuning, but nothing happens upon playback. In fact no matter what expression I choose to edit I am not getting the desired result. Is there something that I am missing when setting up note expression for Groove Agent? I’m using Cubase 13 and the latest version of Groove Agent.