[Blender] Sculpting brush is consistently square-shaped?

Zablorg

I'm using a clay-strip subtraction brush in Blender, and no matter what I do, the indentation is consistently square. You can see the sort of shape I'm getting from it in the bottom-right corner of the above image.

I've even loaded up a circular texture mask to try to fix it, but this seems to have no effect.

Can anyone advise what I can do to fix this and get round brushstrokes again?

Zablorg

Seems this may just be an intrinsic property of the Clay Strips brush? I didn't seem to notice it before. It's also kind of strange that it doesn't seem to be respecting the texture I'm using, either