Also, check your USB drivers and your chipset drivers. Make sure you don’t have any USB power saving features enabled that could be fucking with the driver
Thanks for this suggestion! It does seem USB related, because if the power stays on and I could just use the mouse and keep working, but the pen and buttons stop working, that would suggest data isn't going from the tablet to the pc anymore. I looked up the USB power options and disabled an option that selectively powers down USB devices. I'll try it out and see what happens and update this post accordingly.