If your driver for your XP-Pen product is not working after installation or after you reboot your computer the pen pressure functionality stops working, just follow these quick steps to help fix the issue. This has been the bane to my existence for the past two years, and it really messed with my ability to be able to use my product anytime I wanted. I'll list the driver down below.
XP-Pen Artist 22 driver : https://www.xp-pen.com/download-60.html