pressure sensitivity doesn't work for Cintiq pro 24
I'm on Windows 10 (64 bit) and I'm currently using Cintiq Pro 24 but although I kept my settings from before the device upgrade (Wacom Intuos 4) plus tried to find a fix, the pressure sensitivity for my Cintiq doesn't work while it reacts properly in some other programs (I tested it on Krita and Sketchbook Express which I don't normally use, they work correctly as far as I can tell), meaning the Cintiq itself is well configured and the problem is most likely in Gimp. I do have the brush Dynamics: Pressure set to Opacity (hope I translated it well enough ) as I want but it goes 100% and wobbly (which doesn't happen on the other artprograms).
I use 2.6 (the newer versions don't suit my workflow at all, I never managed to transition to newer interfaces) but I also tried with the most recent stable 2.10.something but I'm having the same issue on both versions. I tried to find a sollution all day (and not forgetting to restart inbetween) with no results, so I need help at this point. Fix for 2.6 highly prefered over the recent since I guess I can't get used to the different interface etc. (I got a device upgrade to speed up my process and re-learning pretty much a new program would defeat the purpose and, worse, prevent me from keeping my drawing style which I didn't manage to reproduce in any other software I tried.)