Recently my Surface suddenly stopped recognizing my pen tip. It recognizes the buttons (i.e., opens OneNote when I tap the button on the back) but won't recognize the pen tip. I've poked around before in the HID device list when turning off the touch screen for drawing, so I thought I might have left one of those turned off. But as far as I can tell, they're all turned on. I reinstalled the pen driver but that did nothing. If anybody here has any ideas before I take it in, please let me know. Thank you!