I have a really weird intermittent issue with Krita. Very frequently krita will get confused about the tracking of the pen on the canvas, the size of the pen input area (i.e. which part of the screen is tracked), the orientation (sometimes moving the stylus left/right moves the pen up/down) etc. This only seems to impact the canvas (i.e. the drawing pen)- the application UI (the mouse cursor) always tracks correctly.
I have a video of the current state (showing some such symptoms) here: https://imgur.com/a/gS0XO7O
Apologies for the shaky capture, but hopefully it illustrates the point.

I've had this happen on many occasions; eventually by trial and error, rotating the screen, closing and restarting krita, rebooting, setting the screen resolution (shift+tap) and repeating these in any combination I can, eventually, by dumb luck or sheer coincidence, things will start working again. But, I don't know the secret to the technique, and soon it befuddles itself again and I'm left floundering once again.

Can anyone identify a cause? Or a reliable solution?

To clarify what's happening in the video, when I mouseover the toolbar at the top of the window the pen tracking starts to work normally (although with no pressure sensitivity). But whenever the stylus goes below a certain point about 1/3 of the way down the screen, the brush position shoots off to the top of the window, nowhere near the actual stylus position. Moving the stylus way down to the bottom of the screen shows that the pen is clearly tracking the stylus (and pressure sensitivity is now working) but there's a huge offset of 1/3rd of the screen!

Well it seems like this time setting the input resolution to '1754 x 800' (rather than my actual screen res of 1280 x 800) seems to have done the trick. Though I need to manually change that each time I rotate the screen.
There are times that this works without such fiddles though, so there's obviously a system that sometimes works, but needs a little debugging.
I'm just happy to be able to use my tablet again.



For now, at least...

Spoke too soon, those numbers don't work any more. Tracking is all over the place again.

Can you report a bug to bugs.kde.org in the product Krita with a tablet log attached? It's also pretty likely this bug could be resolved with winink, but I see you're using windows 7 and we don't have access to the winink api on windows 7 :/

Thanks for the reply TheraHedwig! In making the logs I actually managed to make a little progress in possibly making this reproducible!
When I re-opened krita (with my manual settings) it wasn't working. I set the resolution back to automatic detection, and hey presto everything worked! Both landscape and portrait modes could be switched, with Krita's tracking following suit in either mode.
I then left my tablet in portrait mode and rebooted. This time, after opening Krita the tracking was messed up. Using the settings I had previously noted, i set the resolution manually and it started to work again. Of course this needs editing that resolution when the screen is rotated (switching the x and y values), but provided that's done, tracking works correctly in both modes.
I then left my tablet in landscape mode and rebooted. On re-opening krita (manual landscape settings still active), the tracking was again messed up. Going back to automatic made things work again.

I've zipped up logs from all configurations to add to the kde bug, but it looks like the problem is just that the tablet needs to be booted in landscape mode for the automatic resolution detection to work properly. If not, I can fix the resolution manually, but the required manual settings are not just my screen resolution rotated. ¯\_(ツ)_/¯

Hopefully(!) as long as I always go back to landscape mode before rebooting, things will work consistently from now on.

Created KDE bug report: https://bugs.kde.org/show_bug.cgi?id=410932