Had the filter in my Music app set to A-Z by song. But when set it back to by last downloaded it showed the message below:
Clicked on Match my music
Didn’t get any confirmation. The message went away, on the same machine, after a few minutes. Found this link in my screenshots of the issue in my offline screenshots.
http://support.xbox.com/en-US/music-and-video/music/what-is-xbox-music-cloud