Oh my god it works ! Thank you so so so much !
This works for me, just now tried in my CC.
(All my drivers are updates and I'm using an Intuos Pro M)
Have you thought about using the Express Wheel? I have set mine so that it toggles between brush size and rotate canvas with each press of the button.
I prefer to use presets for opacity, along with layer opacity, because I can control it after laying down the strokes, and do so non-destructively. I use Fade for size and opacity when I need to control stroke by stroke, like when doing hair, eyebrows etc. Often times even a single pixel is too thick, but lowering opacity lets you control the 'apparent' line strength.
I don't tend to use stylus buttons that much, other than right click to change the brush preset. It looks like JJ has found a fix for you though.