Firstly, this is the exact same issue as this post I've linked here.
I am able to use my pen to select options as if it were a mouse. When drawing, if I use my mouse, it will not change tbe brush tool currently selected. However as soon as I use my pen it switchs to a completely different brush (which is always the same). My pen's toggle button, (brush/eraser) is also not working anymore. Has anyone had this issue? I havent had any luck in finding an answer. It has also happened in the past with a previous pen but resolved after MONTHS by itself before doing this again.