Hello,
I have a problem with the brush-tool: When I open a jpg-file with Affinity-Photo, I can paint on the background layer with the brush only on the dark areas. As soon as the area has a certain brightness level, the brush no longer works or the stroke doesn’t appear. On the other hand, I can use the drawing pen or the graphic-text-tool over the entire area, regardless of the brightness level. How can this strange behavior be explained or even turned off? I don't know this behavior of the brush from Photoshop or Gimp. Here I can use it as I like on the background layer, without any further adjustments.
With best regards
Jürgen