I'm not sure the versions of your Arch Linux and Ubuntu, but I guess libXss1 or libgconf-2-4 library is missing. In Ubuntu, please make sure these are existing in your machine,
sudo apt search libXss1
sudo apt search libgconf-2-4
If these are missing, install them by the following.
sudo apt-get libXss1
sudo apt-get libgconf-2-4
And relaunch MATLAB to confirm Live Editor is available. Please replace the corresponding package manager commands in Arch Linux.
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