After enabling axis pan and zoom options, I notice that sometimes both axes will zoom with the mouse wheel when only the x axis should. The mouse cursor is definitely in the area below the X axis when this happens. When this happens, it repeats as I continue to turn the mouse wheel until I move the cursor even a small distance. I also see this with the plots example code running the simple demo.
Windows 10
QCustomPlot 2.10
Qt 5.15.2 or 5.15.3
Visual C++ 2019
(It was amazing easy to enable pan and zoom.)