I followed the “Getting Started with Pirate Audio tutorial” but the default mopidy.conf file created by the install.sh script is now missing the [local] section, so you have to add it from scratch rather than modify the existing file as described in the tutorial. Confusingly, it has a [file] section that has what appears to pre-populate the correct location for music (/home/pi/Music) but this is not what is required to get things working.
So, you just need add the following into the modpidy.conf file and it should work…
[local]
media_dir = /home/pi/Music