I have a little more information. I tried exporting my Performer Store playlist on the Media Server and I imported it into MC on my laptop. The laptop will not play any of the songs in that imported playlist, but if I search for the songs in the Performer Store, the laptop plays them fine.
So it seems like there is some kind of a portability issue with the track info for a song in the Perfomer Store that ties it to the MC install where you added the song to the library.
It did not work this way in the past, and it is severely limiting the value of the Perfomer Store.
I've been a subscriber since the debut, and I am quickly getting frustrated with the unreasonable limitations. Can somebody help, so I don't have to abandon my subscription and switch to Spotify?