Can't sculpt grease pencil strokes?

I am having trouble sculpting grease pencil stokes. After drawing a stoke and switching to sculpt mode, the brushes have no effect on the stokes at all.
Is there a step I am missing?

I am using the latest build as of today around 04:00 am- ish. :- (

EDIT: Seems updating my tablet driver solved the issue.

Which tablet? So others know to search.

Huion H950p tablet