Reply To: Masking (clamping) is not working in 2.90.1

Hi Dave,

Sorry for the late reply (I was moving house)
Yes it seems that the masking setup is a little different these days.  

First you need to enable that masking button (previously called clamping)

Then you need to specify which layer you want to be the mask under the “Masks” tab.  (and you can invert it in that tab)

Check out the wiki page here.
https://docs.blender.org/manual/en/latest/grease_pencil/properties/masks.html