[Solved after I reboot the computer] Cannot draw with stylus, it erases instead of drawing

I have got a XP Pen 12 pro, the stylus works fine on softwares like Krita, but in Blender I cannot draw with the stylus : it erases the existing stroke.
I tried with Blender 2.9 or 2.83, I tried both options in Edit > Prefs > Input > Tablet API : automatic or Windows Ink, and relaunch Blender
I can draw with the mouse, but not with the stylus. I am using the correct tool, it only works with the mouse.

Would you know how to solve this?