I have inverted a High Pass live filter layer and am trying to paint back in just the parts that I want. When I hover with the paint brush over the image Affinity Photo creates a trail of black splotches.
Affinity Photo 1.7.1 on macOS 10.13.6
Here is a screen movie: https://drive.google.com/open?id=1viEQnHnmqgz52_vJxko7EZAiJZF_-d4m