did a test with KRITA 4.0 today. same thing. what happens is, KRITA forces my Wacom to "click and hold" for the right click and disables the click on the pen
this function is disabled in my system. magically, KRITA found a way to use it
i guess i could live with that except it only works on the UI and not in the drawing area itself

yes, it is frustrating when every other program works 100%...