I recently installed Windows 8 Pro on my home PC, which is the last computer that needed to be upgraded, and after installing the latest update for the Music app I experienced a strange issue.
I had no problems opening and browsing the Music app but when I started to play a song and switched to Desktop the computer somehow decides to dramatically lower the volume. Switching back to the Music app would bring up the volume automatically.
Since this is a Windows Store app, I couldn’t play with its settings or configuration files to try to determine what could be causing this, so I simply uninstalled the Music app and installed it again which fortunately fixed it.
Anyways, I thought I would post my experience in case there are others out there facing a similar issue.