A support call with a DELL technician didn't help at all. The gentleman suggested replacing the battery of the pen (which I did, and which didn't help at all) and then concluded, that this would be caused by a recent Windows update. Eventually, I found the cause: it is the pen itself. The pen has a small tip in the front that touches the screen for writing. Apparently, the tip is connected to a small switch inside the pen, which got stuck. That's why the screen detected and acted on the pen already when it was only hovering above the screen. I gently pulled on the tiny tip with my fingernails and pulled it out of the pen. It just seems to be a piece of plastic. Then, I gently pushed it back in, but with little force and not all the way. It took a bit of tinkering, but there is a position at which the pen works normally as expected without the hovering problem. Maybe after usage for some time, there has been too much pressure on the pen and with low build quality, the switch gets stuck and the pen starts showing the hovering behaviour? Right now, I'm fine again. If it happens again, I might just exchange the pen under warrenty. As I haven't found any reference to such a solution anywhere on the web, I hope this one helps you, if you have a similar problem.
The pen used to work perfectly fine (on inkspace or other apps like Drawboard PDF). Today, it started to draw on the screen while still hovering above the screen. E.g. while writing, letters are now connected as if they're all in one stroke, as the screen fails to register when I lift the pen to start the next letter. The result is hardly readable. In drawing apps, I end up getting dots and little strokes all over the place, from moving the pen around above the screen. In the past, this was no issue at all. I've used Support Assistant to have all the latest drivers and firmware installed. I've also installed the extra Pen Control app which allows to adjust sensitivity, but that doesn't change the hover behaviour. This is an example of writing the numbers 1 2 3 4 while the pen was working vs. now: [IMAGE]
Pen PN557W on Latitude 7390 2-in-1 draws while hovering