Splotches while hovering while painting over inverted high pass filter layer

[Richard Liu]

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 1.7.2 RC3 on macOS 10.13.6 Here is a screen movie:https://drive.google.com/open?id=1viEQnHnmqgz52_vJxko7EZAiJZF_-d4m

[MEB]

Hi Richard Liu,
Do you mind uploading the afphoto file shown in your movie clip using this link please? Thank you.