Recent changes to multihop require modifying the line numbers in the settings.json file example above. The country/city data are now located on lines 73 and 74, respectively. The fix is simple:
in dom0:
qvm-run -u root --pass-io --no-gui <MULLVAD-DVM> 'sed -i "s/8s/73s/g" /rw/config/rc.local-early'
qvm-run -u root --pass-io --no-gui <MULLVAD-DVM> 'sed -i "s/9s/74s/g" /rw/config/rc.local-early'