Hi SEllis98,
Thank you for your response.
Do you have any other pen you can try on the Surface device? This is for us to really determine the point of failure since you already uninstalled/reinstalled the drivers I have suggested.
If no other pen, you can run theSurface Diagnostic Toolkitand if no changes after running SDT, please resetyour Surface device.
Once done and the pen still draws wavy lines then, we really have to test other pens on the Surface device or try the pen on other apps for us to isolate this issue.
If this helps, feel free to mark this post as an answer. Otherwise, don't hesitate to respond to this thread for assistance and please let us know if you reset the Surface device or whatnot.
Kind Regards,
Crest_Z