Thank you for sharing your solution. The question remains why the save function from the shaders menu doesn't work for you and me, although the RGUI says that it did save the settings.
If you want to dive deeper into the "failed saving config" error, please open another topic about it (for tidiness and all), start any game from that core with verbose logging via the Runcommand menu, try to (fail to) save the config, and post the contents of /dev/shm/runcommand.log in a code block in your new topic. 🙂