Yep, I've tried with basic brushes and with other brushes but nothing.
Just now I made some experiments, and if I select "no color" and black, and I paint with "no color", it works correctly, this is the ss:
But if I just switch the colors that I've selected, that means, if I paint with black, doesn't work, it's like painting in gray instead of full black:
I think this shouldn't work like that, but at least, I found a solution. Hope you guys know what it's going on, here's my Publisher file using Studio Link:Flyers_A4_HPP - copia.afpub