I am relatively new to Affinity Photo, but I’m not new to photo editing apps. Recently, I’ve tried to recreate the dispersion effect within the app. (the same shown in this video: https://m.youtube.com/watch?v=PSF-k_lnSgA&t=192s)
However, whenever I attempt to actually recreate it, my paintbrush is instantly disabled. This usually happens when I attempt to paint over the mask that covers the image that isn’t liquified. Without glitches, the mask would disappear wherever I would paint over it, as it is white and my paintbrush stroke black. For some reason, it just disables the paintbrush all together, and when it does start working (after I edit the layers in the Layers Studio) it just paints over the mask and the image beneath it. I included a cropped photo below. I am unable to paint black over the mask that’s in the selected layer, or vice verse (unable to paint white over the black mask, which is the second layer).