I currently have a 2013 Macbook Air and a huion GT 191, I downloaded krita when I had an older Huion pad tablet, everything worked wonderfully, including the pressure sensitivity. When I got my new tablet, a Huion GT 191, everything still worked. After about a month the pressure sensitivity would start glitching or something; while I was drawing it would stop working and only start working if I saved my canvas or restarted Krita, but it would only work for a short time. Eventually it stopped working completely. I've tried deleting the kritarc and kritadisplayrc files, there was no kritaopenglrc file. Still nothing was fixed. I have 4.1.1 and I've reinstalled the tablet driver. Pressure sensitivity works with any other program, including Photoshop, just not Krita. When I tried to do what all the other posts say to do in order to fix it, it doesn't work or I can't even locate what file they're talking about, it doesn't appear in my finder when I search. The tablet tester also doesn't register any pressure sensitivity either. I really loved krita when it worked and I would love to be able to keep using it.

Try to use older Huion drivers; apparently on macOS, some driver updates cause problems. There are two other things to mention. The first is that on macOS, Huion probably only tests their drivers with Photoshop and other well-known applications, which means they don't code their drivers to a certain standard, but just to make them work with those apps. The second is that on macOS, Krita does not have any tablet code at all: we just use what the OS gives us, through the Qt platform. So there's nothing in Krita's code we can change...