Since yesterday I have a big problem with retouching brush - suddenly it went awry. Retouching it's impossible now, I tried enabling/disabling the hardware acceleration, choosing another file format, it's the same.
I've uploaded a video on Youtube, below is the link:
I'm glad I found this little comment. I'm a new user of Helicon Focus (v 7.7.5) and I was struggling with this problem too. Resetting the brushes by right-clicking on all the sliders fixed the problem and made the brushes work again.