The issue:
Stylus depth is no longer being tracked in various applications, it appears to be handled as if it were a mouse.
In gnome-shell it still works normally. I can moe the cursor, press down to simulate a left mouse click. Move windows, select items, etc.
In Xournal++ it appears to act like a touchscreen input, meaning if moved along the canvas it moves the canvas while still displaying the mouse cursor.
In Krita it using the pen does draw lines on the canvas but without pressure sensitivity tracking, so here it acts like the mouse.
Lead up to the issue
The issue appeared after upgrading from Ubuntu 18.10 to 19.04. 18.10 was a fresh install.
Modifications that could have had a part in causing the stylus issue:
While this doesn't seem to be the causing issue I did change the Xorg configuration as described here and here.
I applied this a month or more before the upgrade and reverting the changes (remove package, remove configuration, reboot) did not fix the problem, so I applied them again.
Tested configurations:
I tried different configurations with the following results:
Using a different OS: ✔️
Then pen works fine (pressure sensitivity etc.) both when booting Windows 10, which device shipped with and when booting a live stick running Ubuntu 19.04
Using a different pen: ❌
The issue persist when using a different pen. I tried using a HP pen but it is also affected by the issue.
Using Wayland: ✔️
Wayland does not suffer from the issue, the pen works properly in Xournalpp (while Krita immideatly crashes when the pen is used on the canvas which is most likely probably unrelated)
I however would prefer not to use Wayland as using the pen the pen disables the touchscreen (in hardware/firmare/outside the OS' reach) and re-enables it again afterwards isn't being properly detected in Ubuntu and therefore causes the the touchscreen to stay disabled until reboot (except for the random occurences where it does work after pen use but it seems it depends on a race condition whether the touchscreen is enabled while Linux is looking for it)
Setup:
OS: Ubuntu 19.04 (upgraded from 18.10)
Hardware: Link (It's the i7 model)
Additional:
Websearches (DDG and Google) with search terms such as "ubuntu stylus no longer working properly after upgrade" but neither DuckDuckGo nor Google returned results that applied to my situation.
TL;DR:
Stylus no longer gets detected as it should. Issue seems to be limited to X11 on Ubuntu 19.04 but only after upgrading from 18.10, as a live 19.04, Windows 10 and Wayland all work but using a different pen doesn't.
