Hey @jochen I noticed the same issue. I think I fifured out what was happening. If you look at the log - the command mopidy local scan is actually looking for its config files somewhere else:
2015-01-24 18:41:31,358 - INFO Starting Mopidy 0.19.5
2015-01-24 18:41:34,579 - INFO Loading config from: builtin defaults, /etc/xdg/mopidy/mopidy.conf, /root/.config/mopidy/mopidy.conf, command line options
Instead of at /etc/mopidy/mopidy.conf (where there is a symbolic link).
here is how to fix it - assuming you are ssh’d into your PiMusicBox machine as root user - run the following command to remove the old mopidy.conf and replace with a symbolic link to the musicbox version. In a terminal: