Have the S Pen issues been fixed yet? Last times I've tried upgrading beyond 7.1.2 I've encountered the same issue, posted here and haven't seen it go anywhere. It's possible Lineage users for this phone aren't using many art apps? Last time I tried and posted was November, I'm curious if somebody can test it out for me on a recent build.
Download an art app like artflow or Autodesk SketchBook, start drawing a line with the spen, keep the pen on the screen, then touch the screen with a finger while the pen is still down. Does the line disappear that the pen was drawing? This was plaguing all the 8.x builds and is the reason I'm still on 7.x. On 7.x (and earlier), finger touches don't abort the spen event, so accidental palm or finger touches don't abort pen lines that aren't 'finished' by lifting the pen off the screen.
If somebody could try this out I'd be infinitely appreciative.
Thanks,
Levi