Tested on Ubuntu 20.04
Package: libx11-6
Version: 2:1.6.9-2ubuntu1.1
I just tested develop on 3.3.7 and can confirm that it works on Ubuntu 20.04. I assume this is due to the major version bump in the X11 library (1.6.x vs. 1.7.x). This is very unfortunate, I assume that it is a general problem with that older Bitwig Studio version which still ships lots of the X11 libraries (and their java-side binding, afaict) by itself:
...local/bitwig-studio-3.2.8/opt/bitwig-studio/lib/bitwig-studio$ ls -1
libbase-file-notification-linux.so
libbase-platform.so
libbsd.so.0
libbz2.so.1.0
libcairo-freetype-font-system.so
libcairo-graphics.so
libcairo.so.2
libfreetype.so.6
libgraphics-core.so
libharfbuzz.so.0
liblwjgl.so
libpng16.so.16
libx11-windowing-system.so
libXau.so.6
libxcb-icccm.so.4
libxcb-randr.so.0
libxcb-render.so.0
libxcb-shm.so.0
libxcb.so.1
libxcb-util.so.1
libxcb-xinput.so.0
libxcb-xkb.so.1
libXcursor.so.1
libXdmcp.so.6
libz.so.1
This problem of shipping your binary dependencies and potentially being incompatible with system library versions is a general horror when dealing with closed-source software. Especially in the Linux world, due to the heterogeneity of the systems, as opposed to Windows for example.
In 3.3.7 this seems to have improved in so far, that much less system libraries are shipped alongside Bitwig so that the system version will be used instead. That still requires a certain level of binary compatibility of course, but I think there is a bit less potential for conflict. This is because if you’re lucky and the subset of symbols you use in the application is still ABI compatible with the version you linked against, you might get away with it. Here are the libraries that 3.3.7 ships for comparison:
...local/bitwig-studio-3.3.7/opt/bitwig-studio/lib/bitwig-studio$ ls -1
libbase-file-notification-linux.so
libbase-platform.so
libbase-sound.so
libcairo-freetype-font-system.so
libcairo-graphics.so
libgraphics-core.so
liblwjgl.so
libx11-windowing-system.so
libxcb-imdkit.so.1
Notably, the libx11-windowing-system.so is still there so who knows…
Anyway, I think that the older Bitwig version is just slowly running out of binary compatibility with a modern Linux system. So I guess it’s time for me to renew my update plan when the summer sale starts this year, to get a new version that will hopefully be a little bit less tied to specific system library ABIs.