I always have to enable Right Alt in the “Composition Key” section after every reboot. This is needed, so AltGr works correctly in Chromium based applications (Chrome, Discord, Slack) with my keyboard layout (altgr-weur.eu/linux.html).
Now I’m not sure whether this is actually a bug, or related to some of the config for the layout that is loaded at boot overriding some checkbox settings.
Right Alt isn’t the only checkbox that seems to be overriden. “Right Alt; Shift+Right Alt as Compose” is reset after a reboot (this checkbox also fixes the issue of AltGr not working in Chromium based applications)