In the meantime you may want to update your firmware off of the old release candidate.
Connect to the web interface and upload these zip file as is (do not extract them first) to the system folder.
https://github.com/Duet3D/RepRapFirmware/releases/download/3.0/Duet2and3Firmware-3.0.zip
https://github.com/Duet3D/RepRapFirmware/releases/download/3.1.1/Duet2and3Firmware-3.1.1.zip
Afterwards you should be running firmware 3.1.1 and your config.g should work a lot better. Send M115 to confirm.
Then send M98 P"config.g" and report any error messages.