Use this workaround to access the browser interface:
Regarding HQ, MQ etc. these are sub-folder names used in the Music Store folders. HQ is unused, MQ is for CD rips, and LQ is for the ‘parallel library’ of MP3s you can optionally have made from CD rips. You cannot manually add, edit or remove anything from these folders without causing problems. If you want to store anything other than CD rips look for a folder called Downloads, or create a separate Network Share.